DOCSLIB.ORG

Key to Symbols Matrix Crista Inner Membrane Outer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Key to Symbols Matrix Crista Inner Membrane Outer Cellular respiration We need energy to live, but how do we get it? We eat food and, via the process of respiration, we transfer the energy within this food to energy our bodies can use. Respiration is the chemical process of releasing energy from organic compounds. It is a series of enzyme-controlled reactions in which energy is transferred to produce adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate (Pi). Glycolysis Occurs in cytoplasm Oxidation of glucose ( = one carbon atom) mitochondrion glucose to 2 ATP form pyruvate 2 ADP P – – P hexose bisphosphate KEY TO SYMBOLS Net products: Carbon atom: Coenzyme A: • 2 ATP Phosphate group: P • 2 reduced NAD P – P – triose phosphate • 2 pyruvate NAD 2 ADP reduced 2 ATP Is oxygen YES NAD pyruvate AEROBIC RESPIRATION available? NO Occurs in mitochondrial matrix LINK REACTION CYTOPLASM Removal of hydrogen and carbon dioxide from pyruvate (decarboxylation) pyruvate Net products: NAD • 2 reduced NAD ANAEROBIC reduced • 2 CO2 RESPIRATION Occurs in cytoplasm CO2 NAD • 2 acetyl CoA acetyl Respiration that uses group final electron acceptors acetyl CoA other than oxygen Net ATP yield: 2 ATP (from glycolysis) Occurs in mitochondrial matrix KREBS CYCLE Plants (and some micro- Animals (and some micro-organisms, Complete oxidation of acetyl CoA organisms, e.g. yeast): e.g. Lactobacillus): Net products pyruvate pyruvate (two turns of cycle): reduced NAD reduced NAD • 6 reduced NAD NAD NAD • 2 reduced FAD • 2 ATP (from GTP) ethanol lactate acetyl CoA • 4 CO2 CO2 citrate oxaloacetate CO2 NAD reduced NAD reduced NAD NAD ELECTRON CO2 TRANSPORT CHAIN INTERMEMBRANE Space GDP ADP INNER ATP reduced FAD NAD GTP ATP Using electron transport to power MEMBRANE CYTOCHROME C SYNTHASE FAD reduced NAD + the transport of protons (H+), H+ H+ H leading to the production of ATP H+ – 2e – – – MATRIX Net ATP yield: 2e 2e 2e The amount of ATP made per molecule of glucose 2e– CRISTA varies according to conditions. In theory, each can reduced reduced yield a maximum of 38 ATP, but around 30 is more likely. NAD FAD + ATP + H + H H Pi + Glycolysis and Krebs cycle 4 ATP NAD INNER MEMBRANE 1/2 O + 2e– + 2H+ ADP 10 x reduced NAD (electron transport chain) 30 atp 38 ATP FAD 2 2 x reduced FAD (electron transport chain) 4 atp H O 2 OUTER MEMBRANE CYTOCHROME OXIDASE MITOCHONDRIAL INTERMEMBRANE SPACE MATRIX GLOSSARY Acetyl CoA: An intermediate formed ATP (adenosine triphosphate): A Cytochrome oxidase: Terminal FAD (flavine adenine dinucleotide): GTP (guanosine triphosphate): A NAD (nicotinamide adenine Oxidative phosphorylation: A process in the link reaction by the joining of molecule found in all living cells that is component of the electron transport A coenzyme that acts as a hydrogen molecule produced during the Krebs dinucleotide): A coenzyme that acts as in which mitochondria make ATP using coenzyme A (CoA) and a two-carbon involved in the transfer of energy. Most chain, which oxidises cytochrome c. This acceptor in respiration. FAD accepts cycle that donates a phosphate group a hydrogen acceptor in respiration. NAD the energy released when electrons are compound. This enters the Krebs cycle. of a cell’s ATP is made during respiration. is where oxygen is actually consumed, by hydrogen in the Krebs cycle and becomes to ADP to make ATP. It is also very accepts hydrogen in the link reactions transported from reduced NAD and FAD ADP (adenosine diphosphate): A ATP synthase: An enzyme that catalyses acting as the final electron acceptor and reduced. In the electron transport chain, important elsewhere in the cell. and the Krebs cycle and becomes to oxygen in the electron transport chain. molecule found in all living cells that is the synthesis of ATP in oxidative being converted to water. it transfers electrons from this hydrogen. Hydrogen carrier: A molecule that reduced. In the electron transport chain, Redox reaction: When one substance involved in the transfer of energy. phosphorylation. Decarboxylation: A chemical reaction GDP (guanosine diphosphate): A can accept hydrogen atoms or ions it transfers electrons from this hydrogen. is reduced and another oxidised. It is produced when a phosphate group Coenzyme: Small non-protein organic that releases carbon dioxide (CO2). molecule converted to GTP during and donate them to another carrier. OILRIG: A mnemonic for redox reactions Reduction: The gain of electrons or is removed from ATP, a process that molecules that bind to and are required Electron carrier: A molecule that can the Krebs cycle. Hydrogen carriers include NAD and FAD. – oxidation is loss (of electrons or hydrogen, or the loss of oxygen by releases energy. for the activity of their associated accept one or more electrons and Glycolysis: The splitting of sugar. This Mitochondrion: A rod-shaped body that hydrogen), reduction is gain (of electrons a molecule, atom or ion. or hydrogen). Aerobic: Using oxygen. enzyme. An example is coenzyme A donate them to another in an electron process, in which glucose is oxidised, takes supplies chemical energy to eukaryotic Substrate-level phosphorylation: Anaerobic: Without oxygen. (CoA), which combines with a two- transport chain. They include NAD, FAD place in the cytoplasm. It is the first stage cells (plural: mitochondria). Oxidation: The loss of electrons or A process that makes ATP through carbon compound during the link and the cytochromes. of both aerobic and anaerobic respiration. hydrogen (called dehydrogenation), or the the donation of a phosphate group reaction to form acetyl CoA. gain of oxygen by a molecule, atom or ion. from an intermediate directly to ADP, for example during glycolysis. Big Picture is a free post-16 resource for teachers that explores issues around biology and medicine. www.wellcome.ac.uk/bigpicture/exercise/poster The Wellcome Trust is a charity registered in England and Wales, no. 210183. Its sole trustee is The Wellcome Trust Limited, a company registered in England and Wales, no. 2711000 (whose registered office is at 215 Euston Road, London NW1 2BE, UK). PU-5045.2/22.5K/12–2011/BS.
Load more

Recommended publications
  • T E R R E N C E G . F R
    (3) How are the sites of protein import distributed over the surface of mitochondria and what is their T E R R E N C E G . F R E Y relationship to stable contact sites and crista junctions? We are studying the sites of protein import by microinjection of a protein construct into a giant Structure of Biological mutant of Neurospora. The construct contains an N- Macromolecules and Macromolecular terminal mitochondria target sequence, a stable Assemblies; Membrane Structure and folded protein domain to halt transport into Function; Electron Microscopy and mitochondria, and a colloidal gold particle to enable Image Processing visualization in electron micrographs. The sites of protein import will be mapped and correlated with Our research interests are the structural study the positions of stable contact sites and of crista of biological assemblies by application of biophysical junctions and biochemical methods. More specifically, we apply techniques of high resolution electron (4) What are the changes in mitochondria structure microscopy and digital image processing to study the during apoptosis? Mitochondria play a key role in structures of biological macromolecules, initiating the apoptosis program with the release of macromolecular assemblies, and whole organelles. cytochrome c into the cytosol. We are using Electron Currently we are studying the structure and function of tomography to study the structural changes in mitochondria using state of the art microscopic mitochondrial membranes in order to determine techniques, principally Electron Tomography. whether cytochrome c is released through specific Electron Tomography is a technique which calculates pores or through rupture of the outer membrane the three-dimensional structure from a series of following swelling of the matrix.
    [Show full text]
  • Cardiolipin and Mitochondrial Cristae Organization
    Biochimica et Biophysica Acta 1859 (2017) 1156–1163 Contents lists available at ScienceDirect Biochimica et Biophysica Acta journal homepage: www.elsevier.com/locate/bbamem Cardiolipin and mitochondrial cristae organization Nikita Ikon, Robert O. Ryan ⁎ Children's Hospital Oakland Research Institute, 5700 Martin Luther King Jr. Way, Oakland, CA 94609, United States article info abstract Article history: A fundamental question in cell biology, under investigation for over six decades, is the structural organization of Received 23 December 2016 mitochondrial cristae. Long known to harbor electron transport chain proteins, crista membrane integrity is key Received in revised form 3 March 2017 to establishment of the proton gradient that drives oxidative phosphorylation. Visualization of cristae morphol- Accepted 18 March 2017 ogy by electron microscopy/tomography has provided evidence that cristae are tube-like extensions of the mito- Available online 20 March 2017 chondrial inner membrane (IM) that project into the matrix space. Reconciling ultrastructural data with the lipid Keywords: composition of the IM provides support for a continuously curved cylindrical bilayer capped by a dome-shaped Cardiolipin tip. Strain imposed by the degree of curvature is relieved by an asymmetric distribution of phospholipids in Mitochondria monolayer leaflets that comprise cristae membranes. The signature mitochondrial lipid, cardiolipin (~18% of Cristae IM phospholipid mass), and phosphatidylethanolamine (34%) segregate to the negatively curved monolayer leaf- Membrane curvature let facing the crista lumen while the opposing, positively curved, matrix-facing monolayer leaflet contains pre- Non-bilayer lipid dominantly phosphatidylcholine. Associated with cristae are numerous proteins that function in distinctive Electron transport chain ways to establish and/or maintain their lipid repertoire and structural integrity.
    [Show full text]
  • Redalyc.Antioxidant Activity and Fermentative Metabolism in The
    Semina: Ciências Agrárias ISSN: 1676-546X [email protected] Universidade Estadual de Londrina Brasil Ferreira Larré, Cristina; Leivas Moraes, Caroline; Borella, Junior; do Amarante, Luciano; Deune, Sidnei; Peters, José Antonio Antioxidant activity and fermentative metabolism in the plant Erythrina crista-galli L. under flood conditions Semina: Ciências Agrárias, vol. 37, núm. 2, marzo-abril, 2016, pp. 567-580 Universidade Estadual de Londrina Londrina, Brasil Available in: http://www.redalyc.org/articulo.oa?id=445745368003 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative DOI: 10.5433/1679-0359.2016v37n2p567 Antioxidant activity and fermentative metabolism in the plant Erythrina crista-galli L. under flood conditions Atividade antioxidante e metabolismo fermentativo em plantas de Erythrina crista-galli sob alagamento Cristina Ferreira Larré1*; Caroline Leivas Moraes1; Junior Borella1; Luciano do Amarante2; Sidnei Deuner2; José Antonio Peters2 Abstract This study aimed to evaluate the mechanisms of flood tolerance of the root system of Erythrina crista- galli L. plants by measuring the activity of antioxidant enzymes and oxidative stress components in the leaves and roots. Additionally, the activity of fermentation enzymes in the roots was measured. The following two treatments were used: plants with flooded roots, which were maintained at a given water level above the soil surface, and non-flooded plants, which were used as the control. The measurements were performed at 10, 20, 30, 40, and 50 days after treatment.
    [Show full text]
  • BIOLOGY GLOSSARY (English – Chinese)
    BIOLOGY GLOSSARY (English – Chinese) A Site 核糖体 A 部位 abiotic factor 非生物因子[因素] absorption spectrum 吸收光谱 acclimatization 適應，馴化 accommodation 調節；視覺調節 acetylcholine 乙醛 acetyl CoA 乙酰輔酶 A，乙醯輔酶 A acid 酸 acid precipitation 酸性降水 acoelomate 无体腔[的] acquired immunity 后天性免疫 acrosome 顶体，顶体精子 actin 肌动蛋白 action potential 动作电位 activation energy 活化能 active site 活性部位/ 主动运输 active transport 主动运输 adenylyl cyclase 腺苷酸环化酶 adhesion 粘附 adrenal gland 肾上腺 aerobic 有氧的; 需氧的 agnathan 无颌类 agonistic behavior 格斗行为; 争斗行为 AIDS 愛滋病 aldehyde 醛 aldosterone 醛固酮 Alga 藻类 all-or-none event 全或无事件 allantois 尿囊 allele 等位基因 1 allopatric speciation 异地物种形成 allopolyploid 异源多倍体 allosteric site 变构部位 alpha helix α-螺旋 alternation of generations 世代交替 alveolus 牙槽,肺泡 amino acid 氨基酸 amino group 氨基 amino acyl-tRNA synthetase 氨基酰-tRNA 合成酶 aminocentesis 羊膜穿刺法 amnion 羊膜 amniote 羊膜 amniotic egg 羊膜卵 amphibia 两栖纲 amphipathic molecule • 两亲水脂分子 anaerobic 厌氧的 analogy 类比 androgens 雄激素 aneuploidy 非整倍性 angiosperm 被子植物 anion 阴离子；负离子 anterior 先前的; 前面的 anther 花药 antibiotic 抗生素 antibody 抗体 anticodon 反密码子 antidiuretic hormone (ADH) 抗利尿激素 antigen 抗原 aqueous solution 水溶液 archaebacteria 古细菌 archenteron 原肠 artery 动脉 2 arteriole 小动脉 arteriosclerosis 动脉硬化 asexual reproduction 无性生殖 assortive mating 同型交配 atomic number 原子序数 atomic weight 原子量 ATP (adenosine triphosphate) 三磷酸腺苷 ATP synthase • ATP 合成酶 atrioventricular valve 房室瓣 atrium 心房 autoimmune disease 自身免疫病 autonomic nervous system 自主神经系统 autopolyploid 同源多倍体 autosome 常染色体 autotroph 自养生物 axon 轴突 B cell B 细胞 bacteria (plural) bacterium (single) 细菌 bark 树皮 Barr body 性染色质,巴尔氏小体
    [Show full text]
  • Multicolor 3D MINFLUX Nanoscopy of Mitochondrial MICOS Proteins
    Multicolor 3D MINFLUX nanoscopy of mitochondrial MICOS proteins Jasmin K. Papea,1, Till Stephana,b,1, Francisco Balzarottia,2, Rebecca Büchnera, Felix Langea,b, Dietmar Riedelc, Stefan Jakobsa,b,3, and Stefan W. Hella,d,3 aDepartment of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; bClinic of Neurology, University Medical Center Göttingen, 37075 Göttingen, Germany; cLaboratory of Electron Microscopy, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; and dDepartment of Optical Nanoscopy, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany Contributed by Stefan W. Hell, June 23, 2020 (sent for review May 13, 2020; reviewed by Clemens F. Kaminski and Valentin Nägerl) The mitochondrial contact site and cristae organizing system (MICOS) subunits (8, 9). In humans, MICOS consists of at least seven dif- is a multisubunit protein complex that is essential for the proper ferent subunits, which are part of two MICOS subcomplexes, architecture of the mitochondrial inner membrane. MICOS plays a key namely, the Mic60 and Mic10 subcomplexes. The Mic60 subcomplex role in establishing and maintaining crista junctions, tubular or slit-like encompasses Mic60, Mic25, and Mic19, whereas the Mic10 structures that connect the cristae membrane with the inner boundary subcomplex consists of Mic10, Mic13, Mic26, and Mic27 (10–12). membrane, thereby ensuring a contiguous inner membrane. MICOS is Immunogold electron microscopy demonstrated that Mic60 is enriched at crista junctions, but the detailed distribution of its subunits highly enriched at crista junctions (5, 13). Two-dimensional (2D) around crista junctions is unclear because such small length scales are stimulated emission depletion (STED) nanoscopy suggested that inaccessible with established fluorescence microscopy.
    [Show full text]
  • Full-Text.Pdf
    Cutting Edge: Glycolytic Metabolism and Mitochondrial Metabolism Are Uncoupled in Ag-Activated CD8+ Recent Thymic Emigrants This information is current as of September 25, 2021. Cody A. Cunningham, Suzanne Hoppins and Pamela J. Fink J Immunol published online 1 August 2018 http://www.jimmunol.org/content/early/2018/07/31/jimmun ol.1800705 Downloaded from Supplementary http://www.jimmunol.org/content/suppl/2018/07/31/jimmunol.180070 Material 5.DCSupplemental http://www.jimmunol.org/ Why The JI? Submit online. • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication by guest on September 25, 2021 *average Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2018 by The American Association of Immunologists, Inc. All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. Published August 1, 2018, doi:10.4049/jimmunol.1800705 Cutting Edge: Glycolytic Metabolism and Mitochondrial Metabolism Are Uncoupled in Ag-Activated CD8+ Recent Thymic Emigrants Cody A. Cunningham,*,1 Suzanne Hoppins,† and Pamela J. Fink* Recent thymic emigrants (RTEs) are peripheral T cells imparts lasting functional differences that distinguish that have most recently completed selection and thymic RTE-derived memory cells from mature T cell–derived memory egress and constitute a population that is phenotypi- cells (8).
    [Show full text]
  • Plant Physiology and Plant Development
    Plant Physiology and Plant Development PTS 351 B.Sc. B.Ed. Semester – VI Course Instructor Dr. Gautam Kumar Dr. Gautam Kr. Dept. of Life Sc. 1 Carbon Assimilation Light absorption and energy conversion Carbon dioxide uptake and assimilation Calvin Cycle (C3 Pathway) Hatch-Slack pathway (C4 Pathway) Photorespiration (C2 Pathway)/Glycolate metabolism Dr.Gautam Kr. Dept. of Life Sc. 2 • Visible light is electromagnetic radiation of wavelengths 400 to 700 nm, a small part of the electromagnetic spectrum ranging from violet to red. • The energy of a single photon (a quantum of light) is greater at the violet end of the spectrum than at the red end; shorter wavelength (and higher frequency) corresponds to higher energy. Dr.Gautam Kr. Dept. of Life Sc. 3 Solar energy as the ultimate source of all biological energy Photosynthetic organisms use the energy of sunlight to manufacture glucose and other organic products, which heterotrophic cells use as energy and carbon sources. The light reactions of photosynthesis generate energy rich NADPH and ATP at the expense of solar energy. These products are used in the carbon assimilation reactions, which occur in light or darkness, to reduce CO2 to form trioses and more complex compounds (such as glucose) derived from trioses. Dr.Gautam Kr. Dept. of Life Sc. 4 Absorption of visible light by Photo-pigments Plants are green because their pigments absorb light from the red and blue regions of the spectrum, leaving primarily green light to be reflected or transmitted Absorption spectra of the pigments with the spectrum of sunlight reaching the earth’s surface Dr.Gautam Kr.
    [Show full text]
  • A Thermodynamic Model Describing the Nature of the Crista Junction; a Structural Motif in the Mitochondrion
    Working Title: A thermodynamic model describing the nature of the crista junction; a structural motif in the mitochondrion. Christian Renken†*, Gino Siragusa‡, Guy Perkins§, Lance Washington†, Jim Nulton‡, Peter Salamon‡, and Terrence G. Frey†§. †Department of Biology San Diego State University, San Diego, CA 92185 ‡Department of Physics San Diego State University, San Diego, CA 92185 §National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, CA Key Words: electron tomography, membrane topology, mitochondria, modeling, spontaneous curvature. *To whom correspondence should be addressed: Christian Renken Wadsworth Center, NY State Dept. Health Empire State Plaza, P.O.Box 509 Albany, NY 12201-0509 Tel: 518-473-0202 Fax: 518-474-7992 Email:[email protected] Abstract: The use of electron tomography has allowed the three-dimensional membrane topography of the mitochondrion to be better understood. The most striking feature of this topology is the crista junction, a structure that may serve to divide functionally the inner-membrane and inter-membrane spaces. In situ these junctions seem to have a preferred size and shape independent of the source of the mitochondrion with few exceptions. When mitochondria are isolated and have a condensed matrix the crista junctions enlarge and become non-discrete. Upon permeation of the inner membrane and subsequent swelling of the matrix space, the uniform circular nature of the crista junction reappears. We examine the distribution of shapes and sizes of crista junctions and suggest a thermodynamic model that explains the distribution based on current theories of bilayer membrane shapes. The theory of spontaneous curvature shows the circular junction to be a thermodynamically stable structure whose size and shape is influenced by the relative volume of the matrix.
    [Show full text]
  • Cellular Respiration How Is Energy Transferred and Transformed in Living Systems? Why ?
    Cellular Respiration How is energy transferred and transformed in living systems? Why ? Living organisms display the property of metabolism, which is a general term to describe the processes carried out to acquire and use energy. We know that people need to eat, and in our foods are various kinds of nutrients that our cells use. One large group of nutrients in our foods is carbohydrates, which supply our cells with glucose (C6H12O6). So the question is: How does the food we chew and swallow fuel our cells? Model 1 – Glycolysis Cell membrane NAD NADH ADP ATP ADP NAD ! = pyruvic acid (3 C) ATP NADH = glucose (6 C) = mitochondrion = nucleus NUCLEUS 1. Refer to Model 1. a. What is represented by the hexagon? GLUCOSE b. How many carbon atoms (C) are in one molecule of glucose? SIX 2. Refer to Model 1. a. What is represented by the triangles? PYRUVIC ACID b. How many carbon atoms (C) are in one molecule of pyruvic acid? THREE 3. In the process of glycolysis, what happens to glucose after it crosses the cell membrane into the cytoplasm of the cell? GLUCOSE IS BROKEN DOWN INTO PYRUVIC ACID (2) Cellular 1 Respiration Read This! Glycolysis occurs in the cytoplasm of cells and does not require the presence of oxygen. Therefore, the process is anaerobic. It is the first step used by cells to extract energy from glucose in the form of ATP. ATP can be directly used by cells. 4. Thinking about the number of carbon atoms in glucose and in pyruvic acid, explain why there is one molecule of glucose on the left side of the arrow and two molecules of pyruvic acid on the right side of the arrow.
    [Show full text]
  • Electron Transport Generates a Proton Gradient Across the Membrane
    Electron Transport Generates a Proton Gradient Across the Membrane Each of respiratory enzyme complexes couples the energy released by electron transfer across it to an uptake of protons from water in the mitochondrial matrix, accompanied by the release of protons on the other side of the membrane into the intramembrane space. As result, the energetically favorable flow of electrons along the electron- transport chain pumps protons across the membrane out of the matrix. This event creates electrochemical protons across the inner membrane. The Proton Gradient Drives ATP Synthesis The electrochemical proton gradient across the inner mitochondrial membrane is used to drive ATP synthesis in the process of oxidative Phosphorylation. The device that makes this possible is a large membrane-bound enzyme called ATP synthase. This enzymes creates a hydrophilic pathway across the inner mitochondrial membrane that allows protons to follow down their electrochemical gradient. As these ions thread their way through the ATP synthase, they are used to drive the energetically unfavorable reaction between ADP and Pi. 1 Proton Gradients Produce Most of the Cell’s ATP Glycolysis alone produces a net yield of two molecules of ATP for every molecule of glucose, which is the total energy yield for the fermentation process that occur in the absence of oxygen. In contrast, during the oxidative Phosphorylation each pair of electrons donated by NADH produced mitochondria is thought to provide energy for the formation of the about 2.5 molecules of ATP, once one includes the energy needed for transporting this ATP to cytosol. Oxidative Phosphorylation also produces 1.5 ATP molecules per electron pair of FADH2, or from the NADH molecules produced by glycolysis in the cytosol.
    [Show full text]
  • Protein Translocation Pathways of the Mitochondrion
    FEBS 23788 FEBS Letters 476 (2000) 27^31 View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Minireview Protein translocation pathways of the mitochondrion Carla M. Koehler* Department of Chemistry and Biochemistry, Box 951569, University of California, Los Angeles, CA 90095-1569, USA Received 5 May 2000 Edited by Gunnar von Heijne membrane (reviewed by [2^6]). The translocase of the outer Abstract The biogenesis of mitochondria depends on the coordinated import of precursor proteins from the cytosol membrane (TOM) consists of protein import receptors and coupled with the export of mitochondrially coded proteins from the import channel. The receptors (Tom20, 22, 37 and 70, the matrix to the inner membrane. The mitochondria contain an with the number indicating molecular weight) on the mito- elaborate network of protein translocases in the outer and inner chondrial surface recognize targeting information on mito- membrane along with a battery of chaperones and processing chondrial precursors, while components Tom40 and the small enzymes in the matrix and intermembrane space to mediate Tom proteins 5, 6 and 7 form the channel through which the protein translocation. A mitochondrial protein, often with an translocating precursor passes [6]. After passage through the amino-terminal targeting sequence, is escorted through the TOM complex, proteins are sorted via a number of mecha- cytosol by chaperones to the TOM complex (translocase of the nisms either directly to the outer membrane, the intermem- outer membrane). After crossing the outer membrane, the import brane space, or the translocase of the inner membrane (TIM).
    [Show full text]
  • Ionic Strength of the Intermembrane Space of Intact Mitochondria As Estimated with Fluorescein-BSA Delivered by Low Ph Fusion Jorge D
    Ionic Strength of the Intermembrane Space of Intact Mitochondria as Estimated with Fluorescein-BSA Delivered by Low pH Fusion Jorge D. Cortese, A. Laura Voglino, and Charles R. Hackenbrock The Department of Cell Biology and Anatomy, Laboratories for Cell Biology, University of North Carolina, The School of Medicine, Chapel Hill, North Carolina 27599-7090 Abstract. The electrostatic interactions of cytochrome c (octadecylrhodamine B) and the soluble FITC-BSA with its redox partners and membrane lipids, as well fluorescent probe, which report membrane and contents as other protein interactions and biochemical reactions, mixing, respectively. Assays were consistent with a Downloaded from http://rupress.org/jcb/article-pdf/113/6/1331/1061492/1331.pdf by guest on 27 September 2021 may be modulated by the ionic strength of the inter- rapid, low pH-induced vesicle-outer membrane fusion membrane space of the mitochondrion. FITC-BSA was and delivery of FITC-BSA into the intermembrane used to determine the relative value of the mitochon- space. Similar affinities for the ionic strength-depen- drial intermembrane ionic strength with respect to bulk dent change in fluorescence were found for bulk medium, medium external to the mitochondrial outer mem- soluble (9.8 ± 0.8 mM) and intermembrane space- brane. FITC-BSA exhibited an ionic strength-depen- entrapped FITC-BSA (10.2 + 0.6 mM). FITC-BSA con- dent fluorescence change with an affinity in the mM sistently reported an ionic strength in the intermem- range as opposed to its pH sensitivity in the #M range. brane space of the functionally and structurally intact A controlled, low pH-induced membrane fusion pro- mitochondria within ±20% of the external bulk solu- cedure was developed to transfer FITC-BSA encapsu- tion.
    [Show full text]