Ting A E, Hazuka C D, Hsu S C, Kirk M D, Bean A J, Scheller R H
Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical Center, CA 94305-5428, USA.
Proc Natl Acad Sci U S A. 1995 Oct 10;92(21):9613-7. doi: 10.1073/pnas.92.21.9613.
Many of the molecules necessary for neurotransmission are homologous to proteins involved in the Golgi-to-plasma membrane stage of the yeast secretory pathway. Of 15 genes known to be essential for the later stages of vesicle trafficking in yeast, 7 have no identified mammalian homologs. These include the yeast SEC6, SEC8, and SEC15 genes, whose products are constituents of a 19.5S particle that interacts with the GTP-binding protein Sec4p. Here we report the sequences of rSec6 and rSec8, rat homologs of Sec6p and Sec8p. The rSec6 cDNA is predicted to encode an 87-kDa protein with 22% amino acid identity to Sec6p, and the rSec8 cDNA is predicted to encode a 110-kDa protein which is 20% identical to Sec8p. Northern blot analysis indicates that rSec6 and rSec8 are expressed in similar tissues. Immunodetection reveals that rSec8 is part of a soluble 17S particle in brain. COS cell cotransfection studies demonstrate that rSec8 colocalizes with the GTP-binding protein Rab3a and syntaxin 1a, two proteins involved in synaptic vesicle docking and fusion at the presynaptic terminal. These data suggest that rSec8 is a component of a high molecular weight complex which may participate in the regulation of vesicle docking and fusion in brain.
许多神经传递所需的分子与酵母分泌途径中从高尔基体到质膜阶段所涉及的蛋白质同源。在已知对酵母囊泡运输后期至关重要的15个基因中，有7个未鉴定出哺乳动物同源物。这些基因包括酵母的SEC6、SEC8和SEC15基因，其产物是与GTP结合蛋白Sec4p相互作用的19.5S颗粒的组成成分。在此，我们报告了Sec6p和Sec8p的大鼠同源物rSec6和rSec8的序列。rSec6 cDNA预计编码一个87 kDa的蛋白质，与Sec6p有22%的氨基酸同一性，rSec8 cDNA预计编码一个110 kDa的蛋白质，与Sec8p有20%的同一性。Northern印迹分析表明rSec6和rSec8在相似的组织中表达。免疫检测显示rSec8是脑中可溶性17S颗粒的一部分。COS细胞共转染研究表明rSec8与GTP结合蛋白Rab3a和Syntaxin 1a共定位，这两种蛋白质参与突触前末端的突触小泡对接和融合。这些数据表明rSec8是一种高分子量复合物的组成成分，可能参与脑中囊泡对接和融合的调节。
