The GTPase switch appears to be almost as old as life itself, and nature has adapted it to a variety of purposes. This two-volume work surveys the major classes of GTPases, including their role in ensuring accuracy during protein translation, a new look at the trimeric G-protein cycle, the molecular function of ARF in vesicle coating, the emerging role of the dynamin family in vesicle transfer, GTPases which activate GTPases during nascent protein translocation, and the many roles of ras-related proteins in growth, cytoskeletal polymerization, and vesicle transfer. 80 chapters contain much previously unpublished data and, at the rate the extended family of GTPases is growing, it is unlikely that it will again sit for a group portrait such as this. Thus, this could well become the standard reference work.

Inhalt

Section I: Biological Importance of GTPase-Driven Switches.- 1 GTPases Everywhere!.- A. Introduction.- B. The GTPase Cycle and the Molecular Switch.- C. Structure of the GTPase Switch.- D. Primary Structures Identify GTPases with Related Functions.- E. Uses of the GTPase Switch: Stoichiometric Activation.- F. Uses of the GTPase Switch: Assembling a Complex.- G. Other Potential Uses of the GTPase Switch.- H. Cascades of GTPases.- I. Perspectives.- References.- 2 Proofreading in the Elongation Cycle of Protein Synthesis.- A. Introduction.- B. General Concepts.- I. Specificity.- II. Proofreading.- C. Parameters of Protein Biosynthesis.- D. EF-Tu-Dependent Kinetic Proofreading.- E. EF-Tu-Independent Error Correction Mechanisms.- I. Peptidyl Transfer.- II. EF-G-Dependent Translocation.- III. Allosteric Linkage Between A and E Sites.- F. Summary.- References.- 3 A New Look at Receptor-Mediated Activation of a G-Protein.- References.- 4 Small GTPases and Vesicle Trafficking: Sec4p and its Interaction with Up- and Downstream Elements.- A. Introduction.- B. The Sec4 Cycle.- I. A Cycle of Sec4 Localization.- II. Intrinsic Properties of Sec4.- III. GTP Binding and Membrane Attachment Are Essential for Sec4 function.- IV. GTP Hydrolysis Is Important for Sec4 function.- C. Accessory Proteins in the Sec4 Cycle.- I. A Specific Sec4 GAP Is Present in Yeast and Mammalian Cells.- II. GDI from Bovine Brain and Yeast Solubilizes Sec4 in a Nucleotide-Specific Fashion.- III. Suppressors from Yeast and Rat Brain Encode Nucleotide Exchange Proteins.- D. A Potential Downstream Effector of Sec4 Function: The Sec8/Secl5 Complex.- References.- 5 Cytoskeletal Assembly: The Actin and Tubulin Nucleotidases.- A. Introduction.- B. The Nucleotidase Cycle in the Polymerization of Actin and Tubulin.- C. Elementary Steps in NTP Hydrolysis on Actin Filaments and Microtubules: The Regulation of Polymer Assembly.- D. Nucleotide and Metal Ion Binding to Actin and Tubulin.- E. Probing the Nucleotidase Mechanism of Actin and Tubulin using AlF4? and BeF3?, H2O.- F. Conclusions.- References.- 6 Dynamin, A Microtubule-Activated GTPase Involved in Endocytosis.- A. Introduction.- B. Structure and Enzymatic Properties.- C. The Drosophila Shibire Gene.- D. Transfection of Dynamin into Cultured Mammalian Cells.- References.- 7 Transmembrane Protein Translocation: Signal Recognition Particle and Its Receptor in the Endoplasmic Reticulum.- A. Introduction.- B. The Signal Recognition Particle and Its Receptor.- C. Protein Translocation Across the Rough Endoplasmic Reticulum Requires GTP.- D. Binding and Hydrolysis of Guanine Ribonucleotides by Signal Recognition Particle and Its Receptor.- E. Site-Directed Mutagenesis of SR?.- F. The Sorting and Targeting Functions of Signal Recognition Particle are GTP Independent.- G. Current Models for GTP Function During Protein Translocation.- References.- 8 GTPases and Actin as Targets for Bacterial Toxins.- A. Introduction.- B. General Features of ADP-Ribosylating Toxins.- C. ADP-Ribosylation of Elongation Factor 2 by Diphtheria Toxin and Pseudomonas aeruginosa Exotoxin A.- I. Introduction.- II. Diphtheria Toxin.- III. Pseudomonas aeruginosa Exotoxin A.- IV. Functional Consequences of the ADP-Ribosylation of Elongation Factor 2.- D. ADP-Ribosylation of G-Proteins.- I. Introduction.- II. Cholera Toxin.- III. Heat-Labile E. coli Enterotoxins.- IV. Functional Consequences of the ADP-Ribosylation of G-Proteins by Cholera- and Heat-Labile E. coli Enterotoxins.- V. Pertussis Toxin.- VI. ADP-Ribosylation of Gi Go, and Gt by Pertussis Toxin.- E. ADP-Ribosylation of Small GTPases.- I. Introduction.- II. C3-Like ADP-Ribosyltransferases.- III. Functional Consequences of the ADP-Ribosylation of Rho Proteins.- IV. ADP-Ribosylation of Small GTPases by Pseudomonas aeruginosa Exoenzyme S.- F. ADP-Ribosylation of Actin.- I. Introduction.- II. Clostridium botulinum C2 Toxin.- III. Other Actin-ADP-Ribosylating Toxins.- IV. Functional Consequences of the ADP-Ribosylation of Actin.- G. Perspectives.- References.- Section II. Structure of the GTPase Switches.- 9 Eukaryotic Translation Factors Which Bind and Hydrolyze GTP.- A. GTPase Factors.- B. Consensus Sequences of GTPases Factors.- C. Evolution of EF-1?.- D. The EF-Tu Family.- E. Structures of the EF-Tu Family.- References.- 10 Heterotrimeric G-Proteins: ?, ?, and ? Subunits.- A. Introduction.- B. Mammalian G-Proteins.- I. ? Subunits.- 1. Isolation of cDNAs and Genomic DNAs.- a) Gs?.- b) Gi?.- c) Go?.- d) Gt? and Ggust?.- e) Gz?.- f) Gq? and G12?.- 2. Comparison of the Amino Acid Sequences.- a) P Region.- b) G? Region.- c) G Region.- d) G? Region.- e) Cholera Toxin ADP-Ribosylation Site.- 3. Sequence Conservation.- 4. Evolutionary Tree.- II. ? ? Subunits.- C. G-Proteins in Lower Eukaryotes.- I. G-Proteins from Saccharomyces cerevisiae.- 1. Two ? Subunits, GPA1 and GPA2.- 2. ? and ? Subunits.- II. G-Proteins from Schizosaccharomyces pombe.- III. G-Proteins from Caenorhabditis elegans.- IV. G-Proteins from Plants.- References.- 11 Molecular Diversity in Signal Transducing G-Proteins.- A. The ? Subunits.- I. Molecular Diversity.- II. ? Subunit Functions.- B. The ? ? Dimers.- References.- 12 Structural Conservation of Ras-Related Proteins and Its Functional Implications.- A. Introduction: The Discovery of Ras and Ras-Related Genes.- B. Sequence Comparisons.- I. The N-Terminal Extension.- II. The Phosphate-Binding Part.- III. The Guanine-Binding Part.- IV. The C-Terminal Extension.- V. The CaaX Motif.- C. Evolutionary Relationships.- I. Construction of a Homology Tree.- II. Insertions and Deletions.- III. Estimation of the Number of Ras-Related Proteins in Mammals.- D. Discussion.- I. Internal Residues.- II. External Residues and Potential Targets for Interacting Proteins.- III. Relation to Other GTPase Families.- IV. Is There a Conserved Functional Mechanism for All Ras-Related Proteins?.- References.- 13 Conformational Switch and Structural Basis for Oncogenic Mutations of Ras Proteins.- A. Introduction.- B. Conformational Switch.- I. Conformational Differences Between GDP- and GTP-Bound Ras Proteins: Switch I and II Regions.- II. Conformational Domino Effect and Frozen Dynamic States.- III. Small Conformational Changes in the Phosphate-Binding Loop, L1.- C. Structural Basis for Oncogenic Mutations.- I. Mutations at Gln-61 and the Stabilization of the Transition State of the ?-Phosphate of GTP.- II. Mutations at Gly-12 and the Stabilization of the Transition State of the ?-Phosphate of GTP.- III. Residues 12 and 13 Form a Type II ?-Turn for Phosphate Binding.- IV. Mutation at Ala-59 and Switch II Conformation.- D. Discussion.- References.- 14 Structural and Mechanistic Aspects of the GTPase Reaction of H-ras p21.- A. Introduction.- B. The Structure of the p21-Triphosphate State.- C. The Structure and Biochemistry of p21 Mutants.- D. The Kinetic Mechanism of the GTPase Reaction.- E. The Kinetic Mechanism of the GAP-stimulated GTPase.- F. GTPase Mechanism.- G. Arguments For and Against the Proposed Mechanism.- H. Role of GAP in the Chemical Mechanism.- I. Conclusion.- References.- 15 Analysis of Ras Structure a…