DOCSLIB.ORG

ABCB6 Is a Porphyrin Transporter with a Novel Trafficking Signal That Is Conserved in Other ABC Transporters Yu Fukuda University of Tennessee Health Science Center

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ABCB6 Is a Porphyrin Transporter with a Novel Trafficking Signal That Is Conserved in Other ABC Transporters Yu Fukuda University of Tennessee Health Science Center University of Tennessee Health Science Center UTHSC Digital Commons Theses and Dissertations (ETD) College of Graduate Health Sciences 12-2008 ABCB6 Is a Porphyrin Transporter with a Novel Trafficking Signal That Is Conserved in Other ABC Transporters Yu Fukuda University of Tennessee Health Science Center Follow this and additional works at: https://dc.uthsc.edu/dissertations Part of the Chemicals and Drugs Commons, and the Medical Sciences Commons Recommended Citation Fukuda, Yu , "ABCB6 Is a Porphyrin Transporter with a Novel Trafficking Signal That Is Conserved in Other ABC Transporters" (2008). Theses and Dissertations (ETD). Paper 345. http://dx.doi.org/10.21007/etd.cghs.2008.0100. This Dissertation is brought to you for free and open access by the College of Graduate Health Sciences at UTHSC Digital Commons. It has been accepted for inclusion in Theses and Dissertations (ETD) by an authorized administrator of UTHSC Digital Commons. For more information, please contact [email protected]. ABCB6 Is a Porphyrin Transporter with a Novel Trafficking Signal That Is Conserved in Other ABC Transporters Document Type Dissertation Degree Name Doctor of Philosophy (PhD) Program Interdisciplinary Program Research Advisor John D. Schuetz, Ph.D. Committee Linda Hendershot, Ph.D. James I. Morgan, Ph.D. Anjaparavanda P. Naren, Ph.D. Jie Zheng, Ph.D. DOI 10.21007/etd.cghs.2008.0100 This dissertation is available at UTHSC Digital Commons: https://dc.uthsc.edu/dissertations/345 ABCB6 IS A PORPHYRIN TRANSPORTER WITH A NOVEL TRAFFICKING SIGNAL THAT IS CONSERVED IN OTHER ABC TRANSPORTERS A Dissertation Presented for The Graduate Studies Council The University of Tennessee Health Science Center In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy From The University of Tennessee By Yu Fukuda December 2008 Portions of Chapter 2 2006 by Nature Publishing Group All other material 2008 by Yu Fukuda All rights reserved ii DEDICATION I would like to dedicate this dissertation to my parents, Toshio and Etsuko Fukuda for nurturing me with constant love and support so that my roots are firmly grounded to withstand any weather. iii ACKNOWLEDGMENTS I would like to acknowledge and thank everyone who contributed to my dissertation work in the past years. First and foremost I would like to thank my research advisor, Dr. John Schuetz, for his willingness to take me as his first graduate student, his patience, his guidance and his trust. He taught me to stay focused on important issues and encouraged me to develop as a scientist. I would like to also thank all the past and present members of the Schuetz lab for their help, friendship and support. A special thanks to Dr. Partha Krishnamurthy for all the advice he has given me and for all the discussions we had together. I would like to also thank Jessie Morgan for her continuous support and for teaching me the ‘Southern’ styles. I would like to thank Dr. Daxi Sun for helping me with plasmid construction initially, Yao Wang for FACS analysis and Dr. Guoqing Du for plasmids. I also like to thank Bath student, Dan Martin, for repeating the pull-down assays. I would also like to extend my gratitude to Dr. Erin Schuetz for her helpful and insightful comments during the lab meetings. I would also like to thank my graduate committee, Dr. Linda Hendershot, Dr. Jim Morgan, Dr. A. P. Naren and Dr. Jie Zheng for taking part in my graduate training, their guidance and their commitment. I would also like to thank Dr. Jufang Shan for homology modeling help, Yi Jin for showing me how to do pulse chase studies, and Dr. Joseph Bryan at Pacific Northwest Diabetes Research Institute for his contribution to the SUR1 experiment. I would also like to thank Flow cytometry lab for running PPIX measurements. A special thanks to fellow graduate students especially my classmates for their support and for their friendship. I would like to thank Dr. Louise Treanor for her friendship. I would like to thank my best friend Patrick Siglin for his continuous support and for motivating me to be the best person I can be. I would also like to express my sincere thanks to Dr. Yasuyuki Igarashi, Dr. Akio Kihara and Dr. Gabor Tigyi for their support and for encouraging me to pursue my doctorate degree in the United States. Last, but certainly not least, I would like to thank my family and friends. Without their support, none of this would have been possible. iv ABSTRACT The ATP-binding cassette (ABC) transporters play an important role as a barrier to protect cells from the accumulation of toxic xenobiotics and metabolites due to their ability to translocate a wide array of compounds across lipid bilayers. However, many ABC transporters, especially the ones localized in the intracellular organelles, are involved in critical biological processes such as antigen presentation. The core unit of ABC transporters contains two functional domains: the membrane spanning domain (MSD) and the nucleotide binding domain. The full transporters contain two of these units in tandem in a single polypeptide, whereas the half transporters only contain one and must homo- or hetero-dimerize in order to exert their functions. A half transporter ABCB6 has been shown to localize in mitochondria and suggested to play a role in iron homeostasis; however, its function remained elusive. Therefore, we aimed to characterize several aspects of ABCB6: identification of substrates, physiological role, transport mechanism and intracellular trafficking. In this study, we show that ABCB6 is a homodimeric mitochondrial outer membrane protein. Furthermore, we identified ABCB6 as a porphyrin transporter that facilitates heme biosynthesis, in which the intermediates must be shuttled between mitochondria and the cytosol. Translocation of substrates by ABC transporters occurs in an ATP-dependent manner, although the role of ATP binding and hydrolysis in the transport process remains controversial. Taking advantage of its ability to bind hemin conjugated to agarose beads, we demonstrate that the ATP binding at the NBD is sufficient to induce a conformational change to a low affinity state in ABCB6. In an attempt to understand how ABCB6 trafficks intracellularly, we identified a post-translational modification that indicates ER to Golgi trafficking during its maturation. Moreover, we identified a novel N-terminal disulfide bond that plays an important role in the ER exit of ABCB6. This disulfide bond motif is found in other ABC family members and the loss of the conserved cysteine residue in ABCC8/SUR1 is the genetic basis for hyperinsulinemic hypoglycemia. Because ER redox status appears to play an important role in the trafficking of these proteins, expression patterns of ABC transporters may be altered in pathophysiological conditions such as diabetes where microsomal redox status is shifted. v TABLE OF CONTENTS CHAPTER 1. INTRODUCTION................................................................................... 1 1.1. Historic Overview: Discovery of P-glycoprotein and ABC Protein Superfamily.... 1 1.2. ABC Transporters................................................................................................. 3 1.2.1. ABC Transporters and MDR Phenotypes ................................................. 7 1.2.2. Physiological Roles of ABC Transporters ................................................ 8 1.2.3. ABC Transporters and Diseases/Phenotypes ...........................................11 1.2.4. Architecture of ABC Transporters...........................................................11 1.2.5. Transport Mechanism..............................................................................14 1.2.6. Regulation of ABC Transporters.............................................................16 1.3. Half Transporters in ABCB Subfamily.................................................................17 1.3.1. ABCB7/Atm1p .......................................................................................18 1.3.2. ABCB10/ABC-me ..................................................................................20 1.3.3. Identification of ABCB6 (PRP/UMAT/MTABC3)..................................20 1.3.4. Transcriptional Regulation of ABCB6.....................................................21 1.4. Heme Biosynthesis...............................................................................................21 1.4.1. Heme Biosynthesis and Diseases.............................................................22 1.4.2. Compounds That Interfere with Heme Biosynthesis................................24 1.4.3. Photodynamic Therapy ...........................................................................25 1.5. Heme and Porphyrin Transporters........................................................................25 1.5.1. Heme Importer: Heme Carrier Protein 1..................................................26 1.5.2. Heme/Porphyrin Exporters......................................................................26 1.5.3. Intracellular Porphyrin Transporters........................................................27 CHAPTER 2. CHARACTERIZATION OF ABCB6 AS A PORPHYRIN TRANSPORTER....................................................................................29 2.1. Introduction .........................................................................................................29 2.2. Experimental Procedures......................................................................................31 2.2.1. Cell Culture and Transfection..................................................................31
Load more

Recommended publications
  • Targeted Sequence Capture and High-Throughput Sequencing in the Molecular Diagnosis of Ichthyosis and Other Skin Diseases
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE providedCA by Elsevier Scott - Publisheret al. Connector Sequence Capture in Molecular Diagnosis of Skin Diseases Immunohistochemical staining indi- 1The Wellcome Trust Center for Human cause of Olmsted syndrome. Am J Hum cated that MBTPS2 is mainly expressed Genetics, Nuffield Department of Clinical Genet 90:558–64 Medicine, University of Oxford, Oxford, UK; Mevorah B, Goldberg I, Sprecher E et al. (2005) in the upper granular layer in normal 2 Centre for Cutaneous Research, The Blizard Olmsted syndrome: mutilating palmo- skin, as previously shown (Aten et al., Institute, Barts & The London School of plantar keratoderma with periorificial 2010); however, in OS skin, MBTPS2 Medicine and Dentistry, Queen Mary keratotic plaques. J Am Acad Dermatol 53: University of London, London, UK; S266–72 was expressed throughout the epi- 3 dermis (Figure 2c). There was no Department of Dermatology, Jundishapur Naiki M, Mizuno S, Yamada K et al. (2012) University of Medical Sciences, Ahvaz, Iran; MBTPS2 mutation causes BRESEK/BRESHECK 4 apparent difference in MBTPS2 locali- Genetic Department, Kerman University of syndrome. Am J Med Genet A 158A:97–102 zation in the skin of a KFSD patient with 5 Medical Sciences, Kerman, Iran and Darwin Oeffner F, Fischer G, Happle R et al. (2009) IFAP the p.N508S mutation (Aten et al., Building, University College London Genetics syndrome is caused by deficiency in MBTPS2, 2010). It is unclear why this is but it Institute, University College London, London, an intramembrane zinc metalloprotease essen- may be because of differences in UK tial for cholesterol homeostasis and ER stress E-mail: [email protected] response.
    [Show full text]
  • EXTENDED CARRIER SCREENING Peace of Mind for Planned Pregnancies
    Focusing on Personalised Medicine EXTENDED CARRIER SCREENING Peace of Mind for Planned Pregnancies Extended carrier screening is an important tool for prospective parents to help them determine their risk of having a child affected with a heritable disease. In many cases, parents aren’t aware they are carriers and have no family history due to the rarity of some diseases in the general population. What is covered by the screening? Genomics For Life offers a comprehensive Extended Carrier Screening test, providing prospective parents with the information they require when planning their pregnancy. Extended Carrier Screening has been shown to detect carriers who would not have been considered candidates for traditional risk- based screening. With a simple mouth swab collection, we are able to test for over 419 genes associated with inherited diseases, including Fragile X Syndrome, Cystic Fibrosis and Spinal Muscular Atrophy. The assay has been developed in conjunction with clinical molecular geneticists, and includes genes listed in the NIH Genetic Test Registry. For a list of genes and disorders covered, please see the reverse of this brochure. If your gene of interest is not covered on our Extended Carrier Screening panel, please contact our friendly team to assist you in finding a gene test panel that suits your needs. Why have Extended Carrier Screening? Extended Carrier Screening prior to pregnancy enables couples to learn about their reproductive risk and consider a complete range of reproductive options, including whether or not to become pregnant, whether to use advanced reproductive technologies, such as preimplantation genetic diagnosis, or to use donor gametes.
    [Show full text]
  • Impact of Pesticide Use on Health in Developing Countries
    Impact of pesticide use on health in developing countries Proceedings of a symposium held in Ottawa, Canada, 1 7-20 September 1990 IDRC CRDI International Development Research Centre Centre de recherches pour le devetoppement international 1 March 1993 Dear Reader/Librarian, IDRC is a public corporation created by the Canadian parliament in 1970 to help developing countries find viable solutions to their problems through research. At the 1992 Earth Summit, IDRC's mandate was broadened to emphasize sustainable development issues. As part of IDRC's strengthened commitment to global action and harüony, we are pleased to send you a complimentary copy of our most recent publication: The impact of pesticide use on health in developing countries (March 1993, 352 pages, 0-88936-560-1, $17.95). The first part of this book presents a brief survey of the global situation and the results of twelve epidemiological studies carried out by researchers from Africa, Latin America, Asia and the Middle East. These focus on poisonings resulting from organophosphates, herbicides, and pyrethroids. The second part illustrates the role of the process of development, production, spraying techniques and legislation in protecting the health of workers. A discussion of the benefits and modalities of access to pertinent information for the prevention of pesticide poisonings is provided in the third section. Finally, in the fourth section, consideration is given to the advantages and disadvantages of certain alternatives to the use of synthetic pesticides in agriculture and public health, such as botanical pesticides and integrated pest management strategies. We hope this book is a valuable addition to your collection.
    [Show full text]
  • Iron Depletion Reduces Abce1 Transcripts While Inducing The
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 22 October 2019 doi:10.20944/preprints201910.0252.v1 1 Research Article 2 Iron depletion Reduces Abce1 Transcripts While 3 Inducing the Mitophagy Factors Pink1 and Parkin 4 Jana Key 1,2, Nesli Ece Sen 1, Aleksandar Arsovic 1, Stella Krämer 1, Robert Hülse 1, Suzana 5 Gispert-Sanchez 1 and Georg Auburger 1,* 6 1 Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main; 7 2 Faculty of Biosciences, Goethe-University Frankfurt am Main, Germany 8 * Correspondence: [email protected] 9 10 Abstract: Lifespan extension was recently achieved in Caenorhabditis elegans nematodes by 11 mitochondrial stress and mitophagy, triggered via iron depletion. Conversely in man, deficient 12 mitophagy due to Pink1/Parkin mutations triggers iron accumulation in patient brain and limits 13 survival. We now aimed to identify murine fibroblast factors, which adapt their mRNA expression 14 to acute iron manipulation, relate to mitochondrial dysfunction and may influence survival. After 15 iron depletion, expression of the plasma membrane receptor Tfrc with its activator Ireb2, the 16 mitochondrial membrane transporter Abcb10, the heme-release factor Pgrmc1, the heme- 17 degradation enzyme Hmox1, the heme-binding cholesterol metabolizer Cyp46a1, as well as the 18 mitophagy regulators Pink1 and Parkin showed a negative correlation to iron levels. After iron 19 overload, these factors did not change expression. Conversely, a positive correlation of mRNA levels 20 with both conditions of iron availability was observed for the endosomal factors Slc11a2 and Steap2, 21 as well as for the iron-sulfur-cluster (ISC)-containing factors Ppat, Bdh2 and Nthl1.
    [Show full text]
  • Protein Identities in Evs Isolated from U87-MG GBM Cells As Determined by NG LC-MS/MS
    Protein identities in EVs isolated from U87-MG GBM cells as determined by NG LC-MS/MS. No. Accession Description Σ Coverage Σ# Proteins Σ# Unique Peptides Σ# Peptides Σ# PSMs # AAs MW [kDa] calc. pI 1 A8MS94 Putative golgin subfamily A member 2-like protein 5 OS=Homo sapiens PE=5 SV=2 - [GG2L5_HUMAN] 100 1 1 7 88 110 12,03704523 5,681152344 2 P60660 Myosin light polypeptide 6 OS=Homo sapiens GN=MYL6 PE=1 SV=2 - [MYL6_HUMAN] 100 3 5 17 173 151 16,91913397 4,652832031 3 Q6ZYL4 General transcription factor IIH subunit 5 OS=Homo sapiens GN=GTF2H5 PE=1 SV=1 - [TF2H5_HUMAN] 98,59 1 1 4 13 71 8,048185945 4,652832031 4 P60709 Actin, cytoplasmic 1 OS=Homo sapiens GN=ACTB PE=1 SV=1 - [ACTB_HUMAN] 97,6 5 5 35 917 375 41,70973209 5,478027344 5 P13489 Ribonuclease inhibitor OS=Homo sapiens GN=RNH1 PE=1 SV=2 - [RINI_HUMAN] 96,75 1 12 37 173 461 49,94108966 4,817871094 6 P09382 Galectin-1 OS=Homo sapiens GN=LGALS1 PE=1 SV=2 - [LEG1_HUMAN] 96,3 1 7 14 283 135 14,70620005 5,503417969 7 P60174 Triosephosphate isomerase OS=Homo sapiens GN=TPI1 PE=1 SV=3 - [TPIS_HUMAN] 95,1 3 16 25 375 286 30,77169764 5,922363281 8 P04406 Glyceraldehyde-3-phosphate dehydrogenase OS=Homo sapiens GN=GAPDH PE=1 SV=3 - [G3P_HUMAN] 94,63 2 13 31 509 335 36,03039959 8,455566406 9 Q15185 Prostaglandin E synthase 3 OS=Homo sapiens GN=PTGES3 PE=1 SV=1 - [TEBP_HUMAN] 93,13 1 5 12 74 160 18,68541938 4,538574219 10 P09417 Dihydropteridine reductase OS=Homo sapiens GN=QDPR PE=1 SV=2 - [DHPR_HUMAN] 93,03 1 1 17 69 244 25,77302971 7,371582031 11 P01911 HLA class II histocompatibility antigen,
    [Show full text]
  • ABCG1 (ABC8), the Human Homolog of the Drosophila White Gene, Is a Regulator of Macrophage Cholesterol and Phospholipid Transport
    ABCG1 (ABC8), the human homolog of the Drosophila white gene, is a regulator of macrophage cholesterol and phospholipid transport Jochen Klucken*, Christa Bu¨ chler*, Evelyn Orso´ *, Wolfgang E. Kaminski*, Mustafa Porsch-Ozcu¨ ¨ ru¨ mez*, Gerhard Liebisch*, Michael Kapinsky*, Wendy Diederich*, Wolfgang Drobnik*, Michael Dean†, Rando Allikmets‡, and Gerd Schmitz*§ *Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, 93042 Regensburg, Germany; †National Cancer Institute, Laboratory of Genomic Diversity, Frederick, MD 21702-1201; and ‡Departments of Ophthalmology and Pathology, Columbia University, Eye Research Addition, New York, NY 10032 Edited by Jan L. Breslow, The Rockefeller University, New York, NY, and approved November 3, 1999 (received for review June 14, 1999) Excessive uptake of atherogenic lipoproteins such as modified low- lesterol transport. Although several effector molecules have been density lipoprotein complexes by vascular macrophages leads to proposed to participate in macrophage cholesterol efflux (6, 9), foam cell formation, a critical step in atherogenesis. Cholesterol efflux including endogenous apolipoprotein E (10) and the cholesteryl mediated by high-density lipoproteins (HDL) constitutes a protective ester transfer protein (11), the detailed molecular mechanisms mechanism against macrophage lipid overloading. The molecular underlying cholesterol export in these cells have not yet been mechanisms underlying this reverse cholesterol transport process are characterized. currently not fully understood. To identify effector proteins that are Recently, mutations of the ATP-binding cassette (ABC) trans- involved in macrophage lipid uptake and release, we searched for porter ABCA1 gene have been causatively linked to familial HDL genes that are regulated during lipid influx and efflux in human deficiency and Tangier disease (12–14).
    [Show full text]
  • Ncomms6419.Pdf
    ARTICLE Received 6 Jun 2014 | Accepted 29 Sep 2014 | Published 7 Nov 2014 DOI: 10.1038/ncomms6419 OPEN Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter Nina Grossmann1,*, Ahmet S. Vakkasoglu2,*, Sabine Hulpke1, Rupert Abele1, Rachelle Gaudet2 & Robert Tampe´1,3 The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the conserved aspartate, which coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. Our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate. 1 Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Max-von-Laue-Street 9, D-60438 Frankfurt/M., Germany. 2 Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, Massachusetts 02138, USA. 3 Cluster of Excellence Frankfurt—Macromolecular Complexes, Goethe-University Frankfurt, Max-von-Laue-Street 9, D-60438 Frankfurt/M., Germany. * These authors contributed equally to this work.
    [Show full text]
  • ABCB7 Gene ATP Binding Cassette Subfamily B Member 7
    ABCB7 gene ATP binding cassette subfamily B member 7 Normal Function The ABCB7 gene provides instructions for making a protein known as an ATP-binding cassette (ABC) transporter. ABC transporter proteins carry many types of molecules across membranes in cells. The ABCB7 protein is located in the inner membrane of cell structures called mitochondria. Mitochondria are involved in a wide variety of cellular activities, including energy production, chemical signaling, and regulation of cell growth and division. In the mitochondria of developing red blood cells (erythroblasts), the ABCB7 protein plays a critical role in the production of heme. Heme contains iron and is a component of hemoglobin, the protein that carries oxygen in the blood. The ABCB7 protein is also involved in the formation of certain proteins containing clusters of iron and sulfur atoms (Fe-S clusters). Researchers suspect that the ABCB7 protein transports Fe-S clusters from mitochondria, where they are formed, to the surrounding cellular fluid (cytosol), where they can be incorporated into proteins. Overall, researchers believe that the ABCB7 protein helps maintain an appropriate balance of iron (iron homeostasis) in developing red blood cells. Health Conditions Related to Genetic Changes X-linked sideroblastic anemia and ataxia At least three mutations in the ABCB7 gene have been identified in people with X-linked sideroblastic anemia with ataxia. Each of these mutations changes a single protein building block (amino acid) in the ABCB7 protein, slightly altering its structure. These changes disrupt the protein's usual role in heme production and iron homeostasis. Anemia results when heme cannot be produced normally, and therefore not enough hemoglobin is made.
    [Show full text]
  • Structures and Functions of Mitochondrial ABC Transporters
    ATP-binding cassette transporters: from mechanism to organism 943 Structures and functions of mitochondrial ABC transporters Theresia A. Schaedler*, Belinda Faust†, Chitra A. Shintre†, Elisabeth P. Carpenter†, Vasundara Srinivasan‡, Hendrik W. van Veen§ and Janneke Balk1 *Department of Biological Chemistry and Crop Protection, Rothamsted Research, West Common, Harpenden, AL5 2JQ, U.K. †Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7DQ, U.K. ‡LOEWE center for synthetic microbiology (SYNMIKRO) and Philipps University, D-35043 Marburg, Germany §Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, U.K. John Innes Centre and University of East Anglia, Colney Lane, Norwich, NR4 7UH, U.K. Abstract A small number of physiologically important ATP-binding cassette (ABC) transporters are found in mitochondria. Most are half transporters of the B group forming homodimers and their topology suggests they function as exporters. The results of mutant studies point towards involvement in iron cofactor biosynthesis. In particular, ABC subfamily B member 7 (ABCB7) and its homologues in yeast and plants are required for iron-sulfur (Fe-S) cluster biosynthesis outside of the mitochondria, whereas ABCB10 is involved in haem biosynthesis. They also play a role in preventing oxidative stress. Mutations in ABCB6 and ABCB7 have been linked to human disease. Recent crystal structures of yeast Atm1 and human ABCB10 have been key to identifying substrate-binding sites and transport mechanisms. Combined with in vitro and in vivo studies, progress is being made to find the physiological substrates of the different mitochondrial ABC transporters. Sequence analysis of mitochondrial ABC The ABCB7 group, which includes the ABC transporters transporters of the mitochondria Atm1 in yeast and ATM3 in Arabidopsis, Mitochondria of most eukaryote species harbour 2–4 can be found in virtually all eukaryotic species.
    [Show full text]
  • Genetic Basis of Sjo¨Gren's Syndrome. How Strong Is the Evidence?
    Clinical & Developmental Immunology, June–December 2006; 13(2–4): 209–222 Genetic basis of Sjo¨gren’s syndrome. How strong is the evidence? JUAN-MANUEL ANAYA1,2, ANGE´ LICA MARI´A DELGADO-VEGA1,2,& JOHN CASTIBLANCO1 1Cellular Biology and Immunogenetics Unit, Corporacio´n para Investigaciones Biolo´gicas, Medellı´n, Colombia, and 2Universidad del Rosario, Medellı´n, Colombia Abstract Sjo¨gren’s syndrome (SS) is a late-onset chronic autoimmune disease (AID) affecting the exocrine glands, mainly the salivary and lachrymal. Genetic studies on twins with primary SS have not been performed, and only a few case reports describing twins have been published. The prevalence of primary SS in siblings has been estimated to be 0.09% while the reported general prevalence of the disease is approximately 0.1%. The observed aggregation of AIDs in families of patients with primary SS is nevertheless supportive for a genetic component in its etiology. In the absence of chromosomal regions identified by linkage studies, research has focused on candidate gene approaches (by biological plausibility) rather than on positional approaches. Ancestral haplotype 8.1 as well as TNF, IL10 and SSA1 loci have been consistently associated with the disease although they are not specific for SS. In this review, the genetic component of SS is discussed on the basis of three known observations: (a) age at onset and sex-dependent presentation, (b) familial clustering of the disease, and (c) dissection of the genetic component. Since there is no strong evidence for a specific genetic component in SS, a large international and collaborative study would be suitable to assess the genetics of this disorder.
    [Show full text]
  • Molecular Insights Into the Human ABCB6 Transporter Guangyuan Song1, Sensen Zhang 1,Mengqitian1, Laixing Zhang1,Runyuguo1, Wei Zhuo 1 and Maojun Yang 1
    Song et al. Cell Discovery (2021) 7:55 Cell Discovery https://doi.org/10.1038/s41421-021-00284-z www.nature.com/celldisc ARTICLE Open Access Molecular insights into the human ABCB6 transporter Guangyuan Song1, Sensen Zhang 1,MengqiTian1, Laixing Zhang1,RunyuGuo1, Wei Zhuo 1 and Maojun Yang 1 Abstract ABCB6 plays a crucial role in energy-dependent porphyrin transport, drug resistance, toxic metal resistance, porphyrin biosynthesis, protection against stress, and encoding a blood group system Langereis antigen. However, the mechanism underlying porphyrin transport is still unclear. Here, we determined the cryo-electron microscopy (cryo- EM) structures of nanodisc-reconstituted human ABCB6 trapped in an apo-state and an ATP-bound state at resolutions of 3.6 and 3.5 Å, respectively. Our structures reveal a unique loop in the transmembrane domain (TMD) of ABCB6, which divides the TMD into two cavities. It restrains the access of substrates in the inward-facing state and is removed by ATP-driven conformational change. No ligand cavities were observed in the nucleotide-bound state, indicating a state following substrate release but prior to ATP hydrolysis. Structural analyses and functional characterizations suggest an “ATP-switch” model and further reveal the conformational changes of the substrate-binding pockets triggered by the ATP-driven regulation. Introduction usually contain 6–12 transmembrane α-helices and pro- 6 1234567890():,; 1234567890():,; 1234567890():,; 1234567890():,; ATP-binding cassette (ABC) transporters, which trans- vide a distinctive substrate-binding site . port a variety of substrates such as nutrients, drugs, and ABCB6 is an 842-amino acid protein that belongs to the ions by hydrolyzing ATP, are a large class of transmem- B subfamily of the ABC transporter.
    [Show full text]
  • ABCA12 (N-16): Sc-48435
    SAN TA C RUZ BI OTEC HNOL OG Y, INC . ABCA12 (N-16): sc-48435 BACKGROUND CHROMOSOMAL LOCATION The ATP binding cassette (ABC) transporters, or traffic ATPases, constitute Genetic locus: ABCA12 (human) mapping to 2q35; Abca12 (mouse) mapping an expansive family of proteins accountable for the transport of a wide to 1 C3. variety of substrates across cell membranes in both prokaryotic and eukary - otic cells. They also aid in the regulation of lipid transport and membrane SOURCE trafficking. ABCA12 (ATP-binding cassette, subfamily A, member 12) contains ABCA12 (N-16) is an affinity purified goat polyclonal antibody raised against two transmembrane (TM) domains, each with six membrane-spanning seg - a peptide mapping within an internal region of ABCA12 of human origin. ments and two nucleotide-binding domains (NBDs), which are located in the cytoplasm. ABCA12 is expressed in normal human keratinocytes (RT-PCR PRODUCT reveals expression in placenta, testis, fetal brain and skin) and is upregulated during keratinization. Immunoelectron microscopy reveals that the ABCA12 Each vial contains 200 µg IgG in 1.0 ml of PBS with < 0.1% sodium azide protein is located in lamellar granules in the upper epidermal keratinocytes and 0.1% gelatin. of human skin. The ABCA12 gene, which synthesizes a 2,595 amino acid Blocking peptide available for competition studies, sc-48435 P, (100 µg protein, may produce an alternative splice variant with an in-frame deletion peptide in 0.5 ml PBS containing < 0.1% sodium azide and 0.2% BSA). leading to truncation of 79 amino acids. APPLICATIONS REFERENCES ABCA12 (N-16) is recommended for detection of ABCA12 of mouse, rat and 1.
    [Show full text]