DOCSLIB.ORG

A. Membrane Functions Biological Membranes Are Composed Of… Membrane Lipid Protein

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A. Membrane Functions Biological Membranes Are Composed Of… Membrane Lipid Protein A. Membrane Functions Biological Membranes are composed of… Membrane Lipid Protein Myelin Sheath 80% 20% Plasma Membrane 50% 50% Mitochondrial 25% 75% Inner Membrane Fig. 5.12: Phospholipids Hydrophilic head 2 Hydrophobic tails Phospholipds are amphipathic molecules (contain both hydrophilic and hydrophobic parts) Phospholipids form Membrane Bilayers Bilayer consisting of two inverted phospholipid layers (leaflets) Hydrophobic ~30 Å ~45 Å Interior (3 nm) (4.5 nm) Hydrophobic interior is an impermeable barrier to passage of hydrophilic molecules, but not to hydrophobic molecules Cholesterol has profound effects on membrane fluidity Fig 7.8: Membrane Fluidity (a) Phospholipid molecules move side-to-side within leaflet easily (lateral diffusion) but do not “flip-flop” across bilayer (transverse diffusion) (b) Phospholipids containing unsaturated acyl chains increase membrane fluidity by reducing packing efficiency (c) Cholesterol reduces membrane fluidity at normal temperatures (reduces phospholipid movement) At low temperatures it keeps membrane fluid (disrupts packing) Membrane Proteins can Move Laterally Within the Lipid Bilayer Membrane proteins labeled with different color fluorescent dyes Supports fluid-mosaic model of a dynamic membrane structure Three Types of Membrane Proteins 1. Integral membrane proteins (transmembrane proteins) Extracellular domain • span the bilayer • transmembrane domain has Transmembrane hydrophobic surface domain • cytosolic and extracellular Cytosolic domains have hydrophilic surfaces domain 2. Lipid-anchored membrane proteins - anchored via a covalently attached lipid 3. Peripheral membrane proteins - interact with hydrophilic lipid head groups or with integral membrane proteins How do proteins cross lipid bilayer membranes? δ- δ+ δ- δ+ Even if the R-groups are hydrophobic, the peptide bond atoms are hydrophilic (polar) and will want to form Hydrogen Bonds; there are no H-bond donors or acceptors in the middle of a lipid bilayer. Fig 7.9: α-Helices Are Commonly Found in Membrane Proteins EXTRACELLULAR SIDE Polar peptide bond atoms N-terminus H-bond with each other. α-helix of 20 amino acids is long enough to α helix cross the bilayer. C-terminus CYTOPLASMIC SIDE Fig 7.12: Membrane Synthesis & Sidedness Fig. 7.9: Functions of Membrane Proteins Signal Enzymes Receptor ATP Transport Enzymatic activity Signal transduction Glyco- protein Cell-cell recognition Intercellular joining Attachment to the cytoskeleton and extra-cellular matrix (ECM) Fig 7.7: Overview of the Plasma Membrane Fibers of extracellular matrix (ECM) bind to some membrane proteins Glyco- Carbohydrate protein Glycolipid EXTRACELLULAR SIDE OF MEMBRANE Cholesterol Microfilaments of cytoskeleton Peripheral linked to some membrane proteins proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE Fig. 7.22: Endocytosis Phagocytosis Pinocytosis Receptor-Mediated Endocytosis EXTRACELLULAR" FLUID Solutes Pseudopodium Receptor Plasma" Ligand membrane Coat proteins Coated" “Food” or" pit other particle Coated" vesicle Vesicle Food" vacuole CYTOPLASM Membrane Transport Energetics of Diffusion Why do molecules diffuse? A difference in concentration contains chemical potential energy. Molecules diffuse to try to equalize concentrations. [A] [A] [A] [A] Fig. 7.13: Diffusion of Solutes Across A Membrane Membrane (cross Molecules of dye section) WATER Net diffusion Net diffusion Equilibrium (a) Diffusion of one solute Net diffusion Net diffusion Equilibrium Net diffusion Net diffusion Equilibrium (b) Diffusion of two solutes Water Movement If a membrane is permeable to water but impermeable to a solute with different concentrations in two compartments, water will move to try to equalize the concentrations on the two sides of the membrane. Membrane permeable to water but impermeable to solute Fig. 7.15: Water Balance of Living Cells Hypotonic Isotonic Hypertonic solution solution solution (a) Animal cell H2O H2O H2O H2O Lysed Normal Shriveled Cell wall H O H O H O H2O (b) Plant cell 2 2 2 Turgid (normal) Flaccid Plasmolyzed Osmosis .
Load more

Recommended publications
  • Spring 2013 Lecture 23
    CHM333 LECTURES 23: 3/25/13 SPRING 2013 Professor Christine Hrycyna LIPIDS III EFFECT OF CHOLESTEROL ON MEMBRANES: - Bulky rigid molecule - Moderates fluidity of membranes – both increases and decreases o Cholesterol in membranes DECREASES fluidity because it is rigid o Prevents crystallization (making solid) of fatty acyl side chains by fitting between them. Disrupts close packing of fatty acyl chains. Therefore, INCREASED fluidity BIOLOGICAL MEMBRANES CONTAIN PROTEINS AS WELL AS LIPIDS: - Proteins are 20-80% of cell membrane - Rest is lipid or carbohydrate; supramolecular assembly of lipid, protein and carbohydrate - Proteins are also distributed asymmetrically - TWO classes of Membrane Proteins: o Integral Membrane Proteins o Peripheral Membrane Proteins 178 CHM333 LECTURES 23: 3/25/13 SPRING 2013 Professor Christine Hrycyna - INTEGRAL MEMBRANE PROTEINS o Located WITHIN the lipid bilayer o Usually span the bilayer one or more times – called transmembrane (TM) proteins o Hydrophobic amino acids interact with fatty acid chains in the hydrophobic core of the membrane o Can be removed from the membrane with detergents like SDS – need to disrupt the hydrophobic interactions § Membrane Disruption Animation: o http://www.youtube.com/watch?v=AHT37pvcjc0 o Function: § Transporters – moving molecules into or out of cells or cell membranes § Receptors – transmitting signals from outside of the cell to the inside - β Barrel Integral Membrane Proteins § Barrel-shaped membrane protein that is made up of antiparallel β-strands with hydrophilic (interior) and hydrophobic (facing lipid tails). § So far found only in outer membranes of Gram-negative bacteria, cell wall of Gram-positive bacteria, and outer membranes of mitochondria and chloroplasts. 179 CHM333 LECTURES 23: 3/25/13 SPRING 2013 Professor Christine Hrycyna - α-Helical Membrane Proteins - Can cross the membrane once or many times and have multiple transmembrane segments.
    [Show full text]
  • Membrane Structure Overview Pathology > Cellular Biology & Genetics > Cellular Biology & Genetics
    Membrane Structure Overview Pathology > Cellular Biology & Genetics > Cellular Biology & Genetics PLASMA MEMBRANE • Phospholipid bilayer: bilayer that comprises mostly phospholipids • Fluid mosaic: mosaic of proteins embedded within a fluid phospholipid bilayer • Selectively permeable: some substances move through passively, others use proteins for transport MEMBRANE COMPONENTS • Phospholipids • Proteins • Cholesterol • Carbohydrates PHOSPHOLIPIDS • Amphipathic: hydrophilic head and hydrophobic fatty acid tails • Form liposomes in aqueous environment • Weak hydrophobic interactions = membrane fluidity • Saturated phospholipids: maximize hydrogens in fatty acid tails, no kinks • Unsaturated phospholipids: double bond produces kink, increases fluidity CHOLESTEROL • Temperature buffer • Moderate temperature: decreases fluidity, lessens lateral movement • Low temperature: increases fluidity, prevents solidification PROTEINS • Includes transmembrane proteins that span the bilayer (other types exist) • Proteins provide about half the mass of the membrane CARBOHYDRATES • Glycoproteins: branched carbohydrates covalently bound to proteins • Glycolipids: carbohydrates covalently bound to lipids (extracellular only) 1 / 5 CLINICAL CORRELATION: Blood types • Carbohydrates on surface of red blood cells must be compatible between donor & recipient in blood transfusion FUNCTIONS OF THE CELL MEMBRANE • Cell communication • Import and export of molecules • Cell growth • Cell motility Eukaryotes have internal membranes within the cell, prokaryotes do not.
    [Show full text]
  • Cell Membrane
    John Lenyo Corrina Perez Hazel Owens Cell Membrane http://micro.magnet.fsu.edu/cells/plasmamembrane/plasmamembrane.html • Cell membranes are composed of proteins and lipids. • Since they are made up of mostly lipids, only certain substances can move through. spmbiology403.blogspot.com •Phospholipids are the most abundant type of lipid found in the membrane. Phospholipids are made up of two layers, the outer and inner layers. The inside layer is made of hydrophobic fatty acid tails, while the outer layer is made up of hydrophilic polar heads that are pointed toward the water. academic.brooklyn.cuny.edu •Membrane structure relies on the tendency of fatty acid molecules to spread on the surface of water. • Membrane proteins (which take up half of the membrane) determine what gets into and leaves the cell. •Glycolipids are found on the outer part of the cell membrane. Single Chain vs. Phospholipid • Single chain lipids were assumed to be the first of those to form cell membranes with the more complex phospholipids evolving later • Phospholipids can be synthesized in an abiotic environment without enzymes now • Phosphoplipid bilayers now make up the plasma cell membranes that regulate movement into and out of prokaryotic and eukaryotic cells. Single chain lipid http://web.nestucca.k12.or.us/nvhs/staff/whitehead/homewor http://clincancerres.aacrjournals.org/content/11/5/2018/F1. k.htm expansion Types of Lipids • Today Plasma Membranes are made primarily of phospholipids • It is thought that early membranes may have been made of simpler fatty acids. http://exploringorigins.org/fattyacids.html Properties of Fatty Acids • They are Ampipathic, meaning that they have a hydrophobic (“water hating”) end and a hydrophilic (water loving”) end.
    [Show full text]
  • Endoplasmic Reticulum-Plasma Membrane Contact Sites Integrate Sterol and Phospholipid Regulation
    RESEARCH ARTICLE Endoplasmic reticulum-plasma membrane contact sites integrate sterol and phospholipid regulation Evan Quon1☯, Yves Y. Sere2☯, Neha Chauhan2, Jesper Johansen1, David P. Sullivan2, Jeremy S. Dittman2, William J. Rice3, Robin B. Chan4, Gilbert Di Paolo4,5, Christopher T. Beh1,6*, Anant K. Menon2* 1 Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada, 2 Department of Biochemistry, Weill Cornell Medical College, New York, New York, United States of a1111111111 America, 3 Simons Electron Microscopy Center at the New York Structural Biology Center, New York, New a1111111111 York, United States of America, 4 Department of Pathology and Cell Biology, Columbia University College of a1111111111 Physicians and Surgeons, New York, New York, United States of America, 5 Denali Therapeutics, South San a1111111111 Francisco, California, United States of America, 6 Centre for Cell Biology, Development, and Disease, Simon a1111111111 Fraser University, Burnaby, British Columbia, Canada ☯ These authors contributed equally to this work. * [email protected] (AKM); [email protected] (CTB) OPEN ACCESS Abstract Citation: Quon E, Sere YY, Chauhan N, Johansen J, Sullivan DP, Dittman JS, et al. (2018) Endoplasmic Tether proteins attach the endoplasmic reticulum (ER) to other cellular membranes, thereby reticulum-plasma membrane contact sites integrate sterol and phospholipid regulation. PLoS creating contact sites that are proposed to form platforms for regulating lipid homeostasis Biol 16(5): e2003864. https://doi.org/10.1371/ and facilitating non-vesicular lipid exchange. Sterols are synthesized in the ER and trans- journal.pbio.2003864 ported by non-vesicular mechanisms to the plasma membrane (PM), where they represent Academic Editor: Sandra Schmid, UT almost half of all PM lipids and contribute critically to the barrier function of the PM.
    [Show full text]
  • Predicting Protein-Membrane Interfaces of Peripheral Membrane
    bioRxiv preprint doi: https://doi.org/10.1101/2021.06.28.450157; this version posted June 29, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Predicting protein-membrane interfaces of pe- ripheral membrane proteins using ensemble machine learning Alexios Chatzigoulas1,2,* and Zoe Cournia1,* 1Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece, 2Depart- ment of Informatics and Telecommunications, National and Kapodistrian University of Athens, 15784 Athens, Greece *To whom correspondence should be addressed. Abstract Motivation: Abnormal protein-membrane attachment is involved in deregulated cellular pathways and in disease. Therefore, the possibility to modulate protein-membrane interactions represents a new promising therapeutic strategy for peripheral membrane proteins that have been considered so far undruggable. A major obstacle in this drug design strategy is that the membrane binding domains of peripheral membrane proteins are usually not known. The development of fast and efficient algorithms predicting the protein-membrane interface would shed light into the accessibility of membrane-protein interfaces by drug-like molecules. Results: Herein, we describe an ensemble machine learning methodology and algorithm for predicting membrane-penetrating residues. We utilize available experimental data in the literature for training 21 machine learning classifiers and a voting classifier. Evaluation of the ensemble classifier accuracy pro- duced a macro-averaged F1 score = 0.92 and an MCC = 0.84 for predicting correctly membrane-pen- etrating residues on unknown proteins of an independent test set.
    [Show full text]
  • An Overview of Lipid Membrane Models for Biophysical Studies
    biomimetics Review Mimicking the Mammalian Plasma Membrane: An Overview of Lipid Membrane Models for Biophysical Studies Alessandra Luchini 1 and Giuseppe Vitiello 2,3,* 1 Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark; [email protected] 2 Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy 3 CSGI-Center for Colloid and Surface Science, via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy * Correspondence: [email protected] Abstract: Cell membranes are very complex biological systems including a large variety of lipids and proteins. Therefore, they are difficult to extract and directly investigate with biophysical methods. For many decades, the characterization of simpler biomimetic lipid membranes, which contain only a few lipid species, provided important physico-chemical information on the most abundant lipid species in cell membranes. These studies described physical and chemical properties that are most likely similar to those of real cell membranes. Indeed, biomimetic lipid membranes can be easily prepared in the lab and are compatible with multiple biophysical techniques. Lipid phase transitions, the bilayer structure, the impact of cholesterol on the structure and dynamics of lipid bilayers, and the selective recognition of target lipids by proteins, peptides, and drugs are all examples of the detailed information about cell membranes obtained by the investigation of biomimetic lipid membranes. This review focuses specifically on the advances that were achieved during the last decade in the field of biomimetic lipid membranes mimicking the mammalian plasma membrane. In particular, we provide a description of the most common types of lipid membrane models used for biophysical characterization, i.e., lipid membranes in solution and on surfaces, as well as recent examples of their Citation: Luchini, A.; Vitiello, G.
    [Show full text]
  • Membrane Proteins Are Associated with the Membrane of a Cell Or Particular Organelle and Are Generally More Problematic to Purify Than Water-Soluble Proteins
    Strategies for the Purification of Membrane Proteins Sinéad Marian Smith Department of Clinical Medicine, School of Medicine, Trinity College Dublin, Ireland. Email: [email protected] Abstract Although membrane proteins account for approximately 30 % of the coding regions of all sequenced genomes and play crucial roles in many fundamental cell processes, there are relatively few membranes with known 3D structure. This is likely due to technical challenges associated with membrane protein extraction, solubilization and purification. Membrane proteins are classified based on the level of interaction with membrane lipid bilayers, with peripheral membrane proteins associating non- covalently with the membrane, and integral membrane proteins associating more strongly by means of hydrophobic interactions. Generally speaking, peripheral membrane proteins can be purified by milder techniques than integral membrane proteins, whose extraction require phospholipid bilayer disruption by detergents. Here, important criteria for strategies of membrane protein purification are addressed, with a focus on the initial stages of membrane protein solublilization, where problems are most frequently are encountered. Protocols are outlined for the successful extraction of peripheral membrane proteins, solubilization of integral membrane proteins, and detergent removal which is important not only for retaining native protein stability and biological functions, but also for the efficiency of downstream purification techniques. Key Words: peripheral membrane protein, integral membrane protein, detergent, protein purification, protein solubilization. 1. Introduction Membrane proteins are associated with the membrane of a cell or particular organelle and are generally more problematic to purify than water-soluble proteins. Membrane proteins represent approximately 30 % of the open-reading frames of an organism’s genome (1-4), and play crucial roles in basic cell functions including signal transduction, energy production, nutrient uptake and cell-cell communication.
    [Show full text]
  • Membrane Fluidity and the Perception of Environmental Signals In
    Progress in Lipid Research 42 (2003) 527–543 www.elsevier.com/locate/plipres Review Membrane fluidity and the perception of environmental signals in cyanobacteria and plants Koji Mikami, Norio Murata* Department of Regulation Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan Accepted 22 April 2003 Abstract Photosynthetic organisms, namely, plants and cyanobacteria, are directly exposed to changes in their environment and their survival depends on their ability to acclimate to such changes. Several lines of evi- dence suggest that temperature stress, such as unusually low or high temperatures, and osmotic stress might be perceived by plants and cyanobacteria via changes in the fluidity of their cell membranes. The availability of techniques for gene-targeted mutagenesis and gene transfer, as well as for the analysis of genomes and transcripts, has allowed us to examine and evaluate this hypothesis and its implications. In this review, we summarize recent studies of the regulation of gene expression by changes in the extent of unsaturation of fatty acids and membrane fluidity, and we present a discussion of the induction of gene expression by environmental stress and of sensors of environmental conditions and relationships between their activity and the fluidity of membranes in cyanobacteria and plants. # 2003 Elsevier Ltd. All rights reserved. Contents 1. Introduction ..........................................................................................................................................................
    [Show full text]
  • The Structure of Biological Membranes
    The Structure of Biological Membranes Func7ons of Cellular Membranes 1. Plasma membrane acts as a selecvely permeable barrier to the environment • Uptake of nutrients • Waste disposal • Maintains intracellular ionic milieau 2. Plasma membrane facilitates communicaon • With the environment • With other cells • Protein secreon 3. Intracellular membranes allow compartmentalizaon and separaon of different chemical reac7on pathways • Increased efficiency through proximity • Prevent fu8le cycling through separaon Composi7on of Animal Cell Membranes • Hydrated, proteinaceous lipid bilayers • By weight: 20% water, 80% solids • Solids: Lipid Protein ~90% Carbohydrate (~10%) • Phospholipids responsible for basic membrane bilayer structure and physical proper8es • Membranes are 2-dimensional fluids into which proteins are dissolved or embedded The Most Common Class of PhospholipiD is FormeD from a Gycerol-3-P Backbone SaturateD FaJy AciD •Palmitate and stearate most common •14-26 carbons •Even # of carbons UnsaturateD FaJy AciD Structure of PhosphoglyceriDes All Membrane LipiDs are Amphipathic Figure 10-2 Molecular Biology of the Cell (© Garland Science 2008) PhosphoglyceriDes are Classified by their Head Groups Phosphadylethanolamine Phosphadylcholine Phosphadylserine Phosphadylinositol Ether Bond at C1 PS and PI bear a net negave charge at neutral pH Sphingolipids are the SeconD Major Class of PhospholipiD in Animal Cells Sphingosine Ceramides contain sugar moies in ether linkage to sphingosine GlycolipiDs are AbunDant in Brain Cells Figure 10-18 Molecular
    [Show full text]
  • The Membrane
    The Membrane Natalie Gugala1*, Stephana J Cherak1 and Raymond J Turner1 1Department of Biological Sciences, University of Calgary, Canada *Corresponding author: RJ Turner, Department of Biological Sciences, University of Calgary, Alberta, Canada, Tel: 1-403-220-4308; Fax: 1-403-289-9311; Email: [email protected] Published Date: February 10, 2016 ABSTRACT and continues to be studied. The biological membrane is comprised of numerous amphiphilic The characterization of the cell membrane has significantly extended over the past century lipids, sterols, proteins, carbohydrates, ions and water molecules that result in two asymmetric polar leaflets, in which the interior is hydrophobic due to the hydrocarbon tails of the lipids. generated a dynamic heterogonous image of the membrane that includes lateral domains and The extension of the Fluid Mosaic Model, first proposed by Singer and Nicolson in 1972, has clusters perpetrated by lipid-lipid, protein-lipid and protein-protein interactions. Proteins found within the membrane, which are generally characterized as either intrinsic or extrinsic, have an array of biological functions vital for cell activity. The primary role of the membrane, among many, is to provide a barrier that conveys both separation and protection, thus maintaining the integrity of the cell. However, depending on the permeability of the membrane several ions are able to move down their concentration gradients. In turn this generates a membrane potential difference between the cytosol, which is found to have an excess negative charge, and surrounding extracellular fluid. Across a biological cell membrane, several potentials can be found. These include the Nernst or equilibrium potential, in which there is no overall flow of a Basicparticular Biochemistry ion and | www.austinpublishinggroup.com/ebooks the Donnan potential, created by an unequal distribution of ions.
    [Show full text]
  • Biological Membranes
    14 Biological Membranes To understand the structure The fundamental unit of life is the cell. All living things are composed of Goal and composition of biological cells, be it a single cell in the case of many microorganisms or a highly membranes. organized ensemble of myriad cell types in the case of multicellular organisms. A defining feature of the cell is a membrane, the cytoplasmic Objectives membrane, that surrounds the cell and separates the inside of the cell, the After this chapter, you should be able to cytoplasm, from other cells and the extracellular milieu. Membranes also • distinguish between cis and trans surround specialized compartments inside of cells known as organelles. unsaturated fatty acids. Whereas cells are typically several microns (μm) in diameter (although • explain why phospholipids some cells can be much larger), the membrane is only about 10 nanometers spontaneously form lipid bilayers and (nm) thick. Yet, and as we will see in subsequent chapters, the membrane is sealed compartments. not simply an ultra-thin, pliable sheet that encases the cytoplasm. Rather, • describe membrane fluidity and how it membranes are dynamic structures that mediate many functions in the is affected by membrane composition life of the cell. In this chapter we examine the composition of membranes, and temperature. their assembly, the forces that stabilize them, and the chemical and physical • explain the role of cholesterol in properties that influence their function. buffering membrane fluidity. The preceding chapters have focused on two kinds of biological molecules, • explain how the polar backbone namely proteins and nucleic acids, that are important in the workings of a membrane protein can be accommodated in a bilayer.
    [Show full text]
  • The Membrane Interface of Chloroplast Signal Recognition Particle-Dependent Protein Targeting
    University of Arkansas, Fayetteville ScholarWorks@UARK Theses and Dissertations 5-2009 The eM mbrane Interface of Chloroplast Signal Recognition Particle-Dependent Protein Targeting Naomi Jane Marty University of Arkansas, Fayetteville Follow this and additional works at: http://scholarworks.uark.edu/etd Part of the Cell Biology Commons, and the Molecular Biology Commons Recommended Citation Marty, Naomi Jane, "The eM mbrane Interface of Chloroplast Signal Recognition Particle-Dependent Protein Targeting" (2009). Theses and Dissertations. 6. http://scholarworks.uark.edu/etd/6 This Dissertation is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ScholarWorks@UARK. For more information, please contact [email protected], [email protected]. THE MEMBRANE INTERFACE OF CHLOROPLAST SIGNAL RECOGNITION PARTICLE-DEPENDENT PROTEIN TARGETING THE MEMBRANE INTERFACE OF CHLOROPLAST SIGNAL RECOGNITION PARTICLE-DEPENDENT PROTEIN TARGETING A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Cell and Molecular Biology By Naomi J. Marty Northeastern State University Bachelor of Science in Biology, 2003 May 2009 University of Arkansas ABSTRACT A novel signal recognition particle (SRP) found in the chloroplast (cpSRP) works in combination with the cpSRP receptor, cpFtsY, to facilitate the post-translational targeting of a family of nuclear-encoded thylakoid proteins to the Alb3 translocase in thylakoid membranes. Work here focused on understanding events at the membrane that take place to ensure targeting of the cpSRP-dependent substrate to Alb3. Specifically, we sought to understand the structural and functional role of membrane binding by cpFtsY, a protein that exhibits the ability to partition between the membrane (thylakoid) and soluble (stroma) phase during protein targeting.
    [Show full text]