Rab Gtpases

"Ypt/Rab GTPases form the largest branch of the Ras-related small GTPase superfamily and regulate intracellular membrane trafficking in all eukaryotes. Since their discovery over two decades ago, a wealth of information has accumulated about the roles that"

This second edition volume expands on the previous edition with a discussion of new research and discoveries in the Rab field. Chapters in this book cover topics such as new information on Rab regulation and localization; interaction; function; and diseases. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and comprehensive, Rab GTPases: Methods and Protocols, Second Edition is a valuable resource for scientists working in the fields of Rab and other small GTPases, and beyond.

This volume covers the latest technological advances in the characterization of the biosynthesis and functions of Rab GTPases and their regulation by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). The book consists of 28 chapters, and starts with an overview of the Rab GTPase family. The next few chapters describe systematic approaches to the identification and classification of Rabs and Rab GAPs, as well as the detection of Rab isoprenylation and membrane distribution. The last few chapters examine the biochemical and functional properties of individual Rabs in the order of exocytic, recycling, and endocytic Rabs. Written in the highly successful Methods of Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and key tips on troubleshooting and avoiding known pitfalls. Instructive and practical, Rab GTPases: Methods and Protocols approaches each topic with great detail and is a valuable resource for researchers and students interested in the field of Rab GTPases.

Rab GTPases are master regulators of membrane trafficking in eukaryotic cells. With GTP bound, they regulate trafficking by recruiting effectors to specific membrane-bound compartments. GTPase-activating proteins (GAPs) stimulate a Rab's intrinsic rate of GTP hydrolysis, thus inactivating the Rab by converting bound GTP to GDP. Regulation of Rab proteins links the formation and breakdown of sequential, Rab-regulated membrane domains in the secretory and endocytic pathways. This thesis presents the characterization of a novel RabGAP, RUTBC1. RUTBC1 binds Rab9 in vitro and in cells through interactions with its N-terminus. Overexpression of RUTBC1 only slightly disrupts MPR trafficking and RUTBC1 does not function as a GAP for Rab9. In vitro biochemical screening of Rab proteins revealed that RUTBC1 has GAP activity toward Rab33b and Rab32. These data suggest that RUTBC1 might function to link inactivation of these Rabs in relation to a Rab9 microdomain, in support of the existence of a Rab cascade at the interface between the Golgi apparatus and endosomes. Depletion of RUTBC1 unexpectedly led to concomitant depletion of Atg16L1. Atg16L1 has an established and essential role in macroautophagy, a highly conserved cellular recycling process. Overexpression of Atg16L1 caused the formation of large puncta in the cytoplasm, which are also labeled by endogenous RUTBC1 and may represent autophagosomes. Atg16L1 is a known Rab33b effector, suggesting that Rab33b, RUTBC1 and Atg16L1 function together to regulate autophagosome formation. Finally, RUTBC2, which is highly related to RUTBC1, also binds specifically to Rab9. In vitro biochemical screening for RUTBC2's Rab substrates showed that RUTBC2 had highest GAP activity toward Rab34 and Rab36, two very similar Rabs thought to play a role in secretion. The difference in substrate specificity between RUTBC1 and RUTBC2 further exemplifies the highly complex integration of diverse membrane trafficking pathways in mammalian cells.

This second of two volumes discusses subfamily proteins which function in molecular and vesicular transport mechanisms inside the cell. In this volume the focus lies on the Rab, Ran and Arf subfamily members. As in Volume 1, the book is written by international renowned scientists in the field of small G-proteins. In elaborate reviews, biochemistry, structure, function and G-protein - effector interactions are described. Together with Volume 1 this book provides an comprehensive state-of-the-art work on small G-proteins (GTPases). It is written for Graduates and Professors in Biochemistry and Cell Biology interested in the mechanism and function of small G-proteins but are extremely valuable for those who want to move into the field.

Rab GTPases now comprise a family of >63 members. They are emerging as the key hub element controlling the membrane architecture of eukaryotic cells. They are intimately involved in vesicle targeting and fusion in both the endocytic and exocytic pathways and direct the assembly and disassembly of protein complexes that include regulators (GEFs and GAPs), effectors (tethers/motors) and fusion components (SNAREs) that control membrane targeting and fusion. During the last 3 years the field has virtually exploded with the identification and characterization of many new Rab proteins and their effectors. Our understanding of how Rab GTPases control membrane function remains at its infancy. This volume of Methods in Enzymology, GTPases Regulating Membrane Targeting and Fusion, provides a wealth of new concepts, approaches and tools to study Rab proteins in the test tube and in living cells that will be of strong benefit to both established laboratories and new investigators in the field to elucidate Rab GTPase function in cellular development, differentiation and proliferation. Comprehensive overview of Rab GTPase phylogeny and systems biology Identification and characterization of Rab GEFs, GAPs and effectors General methodologies to study Rab GTPase function in vitro and in vivo using biochemical, molecular and microscopy approaches

Endocytosis is a fundamental cellular process by means of which cells internalize extracellular and plasma membrane cargos for recycling or degradation. It is important for the establishment and maintenance of cell polarity, subcellular signaling and uptake of nutrients into specialized cells, but also for plant cell interactions with pathogenic and symbiotic microbes. Endocytosis starts by vesicle formation at the plasma membrane and progresses through early and late endosomal compartments. In these endosomes cargo is sorted and it is either recycled back to the plasma membrane, or degraded in the lytic vacuole. This book presents an overview of our current knowledge of endocytosis in plants with a main focus on the key molecules undergoing and regulating endocytosis. It also provides up to date methodological approaches as well as principles of protein, structural lipid, sugar and microbe internalization in plant cells. The individual chapters describe clathrin-mediated and fluid-phase endocytosis, as well as flotillin-mediated endocytosis and internalization of microbes. The book was written for a broad spectrum of readers including students, teachers and researchers.

International Review of Cell & Molecular Biology presents current advances and comprehensive reviews in cell biology—both plant and animal. Articles address structure and control of gene expression, nucleocytoplasmic interactions, control of cell development and differentiation, and cell transformation and growth. * Authored by some of the foremost scientists in the field * Provides up-to-date information and directions for future research * Valuable reference material for advanced undergraduates, graduate students and professional scientists