Fischer von Mollard G, Stahl B, Walch-Solimena C, Takei K, Daniels L, Khoklatchev A, De Camilli P, Südhof T C, Jahn R
Department of Cell Biology, Yale University School of Medicine, New Haven, CT.
Eur J Cell Biol. 1994 Dec;65(2):319-26.
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.
胞吐作用后，突触小泡迅速进行内吞和再循环，但其中涉及的分子机制却鲜为人知。Rab5是一种普遍存在的低分子量GTP结合蛋白，是成纤维细胞内体融合所必需的。我们现已制备了针对大鼠Rab5的多克隆和单克隆抗体，并表明在大鼠脑中，Rab5是一种主要的突触小泡蛋白。用针对小GTP结合蛋白Rab3A和Rab5的抗体或用突触素作为一般突触小泡标记物，从脑中免疫分离囊泡细胞器，结果表明存在含有Rab5或Rab3A或两者的重叠突触小泡群体，这表明这些低分子量GTP结合蛋白与突触小泡存在阶段特异性关联。我们的数据提供了首个生化证据，表明突触小泡再循环涉及一种类似于受体介导的内吞途径的内体中间体。
