title: Localization of Rab5 to synaptic vesicles identifies endosomal intermediate in synaptic vesicle recycling pathway.
abstract: After exocytosis, synaptic vesicles rapidly endocytose and recycle but little is known about the molecular mechanisms involved. Rab5 is a ubiquitous low molecular weight GTP-binding protein required for endosomal fusion in fibroblasts. We have now raised polyclonal and monoclonal antibodies to rat Rab5 and show that in rat brain, Rab5 is a major synaptic vesicle protein. Immunoisolation of vesicular organelles from brain with antibodies to either Rab3A and Rab5 as small GTP-binding proteins or with synaptophysin as general synaptic vesicle marker demonstrates that there are overlapping populations of synaptic vesicles containing either Rab5 or Rab3A or both, suggesting a stage-specific association of these low-molecular weight GTP-binding proteins with synaptic vesicles. Our data provide the first biochemical evidence that synaptic vesicle recycling involves an endosomal intermediate similar to that of the receptor-mediated endocytosis pathway.
authors.affiliation: Department of Cell Biology, Yale University School of Medicine, New Haven, CT.
authors.forename: G
authors.initials: G
authors.lastname: Fischer von Mollard
authors.forename: B
authors.initials: B
authors.lastname: Stahl
authors.forename: C
authors.initials: C
authors.lastname: Walch-Solimena
authors.forename: K
authors.initials: K
authors.lastname: Takei
authors.forename: L
authors.initials: L
authors.lastname: Daniels
authors.forename: A
authors.initials: A
authors.lastname: Khoklatchev
authors.forename: P
authors.initials: P
authors.lastname: De Camilli
authors.forename: T C
authors.initials: TC
authors.lastname: Südhof
authors.forename: R
authors.initials: R
authors.lastname: Jahn
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015415:Biomarkers / Q000737:chemistry; D004705:Endocytosis / Q000502:physiology; D011992:Endosomes / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000032:analysis*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000032:analysis*; D013572:Synaptic Vesicles / Q000737:chemistry*; D020692:rab3 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins
chemical_list: D015415:Biomarkers; D009419:Nerve Tissue Proteins; D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins