Localization of Rab5 to synaptic vesicles identifies endosomal intermediate in synaptic vesicle recycling pathway

• Published in: European journal of cell biology Vol. 65; no. 2; p. 319
• Main Authors: Fischer von Mollard, G, Stahl, B, Walch-Solimena, C, Takei, K, Daniels, L, Khoklatchev, A, De Camilli, P, Südhof, T C, Jahn, R
• Format: Journal Article
• Language: English
• Published: Germany 01.12.1994
• Subjects: Amino Acid Sequence; Base Sequence; Biomarkers - chemistry; Endocytosis - physiology; Endosomes - metabolism; GTP-Binding Proteins - analysis; Molecular Sequence Data; Molecular Weight; Nerve Tissue Proteins - analysis; rab3 GTP-Binding Proteins; rab5 GTP-Binding Proteins; Synaptic Vesicles - chemistry
• ISSN: 0171-9335

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.