Membrane Biogenesis

Many individual aspects of the dynamics and assembly of biological membranes have been studied in great detail. Cell biological approaches, advanced genetics, biophysics and biochemistry have greatly contributed to an increase in our knowledge in this field.lt is obvious however, that the three major membrane constituents - lipids, proteins and carbohydrates- are studied, in most cases separately and that a coherent overview of the various aspects of membrane biogenesis is not readily available. The NATO Advanced Study Institute on "New Perspectives in the Dynamics of Assembly of Biomembranes" intended to provide such an overview: it was set up to teach students and specialists the achievements obtained in the various research areas and to try and integrate the numerous aspects of membrane assembly into a coherent framework. The articles in here reflect this. Statting with detailed contributions on phospholipid structure, dynamics, organization and biogenesis, an up to date overview of the basic, lipidic backbone of biomembranes is given. Extensive progress is made in the research on membrane protein biosynthesis. In particular the post- and co-translational modification processes of proteins, the mechanisms of protein translocation and the sorting mechanisms which are necessary to direct proteins to their final, intra - or extracellular destination have been characterized in detail. Modern genetic approaches were indispensable in this research area: gene cloning, hybrid protein construction, site directed mutagenesis and sequencing techniques elucidated many functional aspects of specific nucleic acid and amino acid sequences.

There are currently a growing number of laboratories actively studying the mechanism by which various biological membranes are assembled. This area of research is still relatively new to biochemists and molecular biologists, but in view of the rapid progress being made, a review of the field at this time is justified. The present volume focuses on the biogenesis of three related membranes. Mitochondria and chloroplasts are semiautonomous organelles whose biogenesis is carried out partly in the external cytoplasm and partly by the organelles themselves. Both membranes are principally concerned with the energy metabolism of the cell, and this commonality of function is reflected in a considerable degree of similarity in their ul trastructure and enzymatic composition. Although the bacterial cell membrane is a much more diversified structure, it also fulfills the basic energy requirements of the cell, and depending on the organism, this can take the form of photosynthesis or oxidative phosphorylation. The addi tional consideration that prokaryotic organisms may, in fact, be the evolu tionary ancestors of mitochondria and chloroplasts, makes it all the more compelling that those interested in biogenesis be aware of new develop ments in each of these three areas. In organizing this book, I felt that the contributors should summarize and bring up to date their own research and review the literature only in sofar as would be necessary to provide the proper perspective for their work.

Membrane proteins and membrane lipids form complex interactive systems that are highly dynamic and able to be studied only by combinations of different in vivo and in vitro techniques. In Membrane Biogenesis: Methods and Protocols, experts in the field present a broad collection of methods to study the biogenesis and function of cellular membranes. Beginning with how membrane lipids or membrane proteins can be studied, this detailed volume continues with sections covering different procedures to investigate the interaction of membrane proteins among each other or with membrane lipids, methods to study the biogenesis of membrane proteins and the dynamics of organelles, as well as protocols for the analyses of the functions or complex organization of membrane proteins. Written in the highly successful Methods in Molecular BiologyTM series format, chapters include introductions to their respective topics, lists of materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Extensive and easily applicable, Membrane Biogenesis: Methods and Protocols provides readers with a comprehensive but still concise collection including both basic protocols of rather general application and more specialized methods for specific and novel techniques.

Membrane proteins and membrane lipids form complex interactive systems that are highly dynamic and able to be studied only by combinations of different in vivo and in vitro techniques. In Membrane Biogenesis: Methods and Protocols, experts in the field present a broad collection of methods to study the biogenesis and function of cellular membranes. Beginning with how membrane lipids or membrane proteins can be studied, this detailed volume continues with sections covering different procedures to investigate the interaction of membrane proteins among each other or with membrane lipids, methods to study the biogenesis of membrane proteins and the dynamics of organelles, as well as protocols for the analyses of the functions or complex organization of membrane proteins. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Extensive and easily applicable, Membrane Biogenesis: Methods and Protocols provides readers with a comprehensive but still concise collection including both basic protocols of rather general application and more specialized methods for specific and novel techniques.

Scientific reviews are now of two complementary types: short, very up-to-date articles, as are found in the Trends series, and the more traditional longer re views, which are more comprehensive but take longer to publish. The Subcellu lar Biochemistry series belongs to the latter category where a number of reviews on a broad topic are collected together in the one volume. It has been the aim of this volume to summarize the present state of knowledge of membrane assembly. It is appreciated that some relevant topics have not been included, and an editor's selection is restricted by the many calls on potential authors who are unable to meet all requests made to them. The absence of a discussion of the roles of lipids is," however, a reflection of the fact that a recent volume in this series, edited by Dr. H. 1. Hilderson, has been devoted to this subject (Vol. 16, Intracellular Transfer of Lipid Molecules), and readers are recommended to this source.

This book provides a comprehensive overview of recent developments in the fast moving field of protein transport across and into intracellular membranes. The soluble and membrane-bound components assisting in these processes are introduced, and their functions described. Besides a detailed analysis of protein translocation across the bacterial plasma membrane, the mechanisms of protein targeting within the eukaryotic cell are discussed with special focus on the transport of proteins to the endoplasmic reticulum, vacuoles, peroxisomes, mitochondria, and chloroplasts. Providing stimulating hypotheses and models, the book is well suited for advanced students, graduate students, and for newcomers to the field seeking a general, yet accurate introduction to present knowledge in membrane transport of proteins.

The incentive for putting together Volume 4 of this series was to review the wealth of new information that has become available in prokaryotic organisms in protein export and membrane biogenesis. Just in the last several years, protein translocation has now been efficiently reconstituted using defined components and the mechanism by which proteins are moved across membrane bilayers is now being examined at a higher resolution. In addition, because of a new technical breakthrough using osmolytes, it is now possible to reconstitute a number of channel proteins, ATPase, receptors, and transporters. In many cases, it is possible to successfully predict the membrane topology of these types of proteins using both "hydrophobicity analysis" and the "positive inside" rule. In this volume, two chapters focus on protein translocation across membranes (Biochemical Analyses of Components Comprising the Protein Translocation Machinery of E. Coli; Protein Translocation Genetics), while several others on how proteins assemble into the ineer membrane of E. Coli (Membrane Protein Assembly; Membrane Insertion of Small Proteins: Evolutionary and Functional Aspects; Pigment-Protein Complex Assembly in Rhodobacter sphaeroides and Rhodobacter Capsulatus). Other sections review recent progress on transporters (Identification and Reconstitution of Anion Exchange Mechanisms in Bacteria; Helic Packing in the C-Terminal Half of Lactose Permease) and signal transduction (Mechanism of Transmembrane Signaling in Osmoregulation) as well as the assembly of prints into the outer membrane (Export and Assembly of Outer Membrane Proteins in E. coli). Although the emphasis of the book is on proteins, the role of phospholipids in controlling various cell surface processes is reviewed (Role of Phospholipids in coli Cell Function). I should point out the reason for the rapid progress in bacteria research is because of the possibility to apply biochemistry and genetics in this organism.