Linstedt A D, Vetter M L, Bishop J M, Kelly R B
Program in Neuroscience, University of California, San Francisco 94143-0534.
J Cell Biol. 1992 Jun;117(5):1077-84. doi: 10.1083/jcb.117.5.1077.
The protein product of the proto-oncogene c-src is a membrane-associated tyrosine kinase of unknown function. Identification of pp60c-src target membranes may elucidate the function of the c-src protein. The available evidence indicates that pp60c-src associates with distinct membranes within single cell types and has different distributions in different cell types. Our experiments demonstrate targeting of pp60c-src to an isolatable and biochemically identified membrane fraction in the neuroendocrine cell line PC12. The c-src protein was found to be specifically associated with synaptic vesicles since: (a) the pp60c-src immunofluorescent pattern overlapped with a synaptic vesicle marker, synaptophysin; (b) a significant proportion (44%) of the pp60c-src from PC12 but not fibroblast postnuclear supernatants was recovered in a small vesicle fraction; (c) an anti-synaptophysin cytoplasmic domain antibody immunodepleted all of the pp60c-src vesicles in this fraction, and (d) pp60c-src copurified during a 100-fold purification of PC12 synaptic vesicles. These results suggest a role for the c-src protein in the regulation of synaptic vesicle function.
原癌基因c-src的蛋白质产物是一种功能未知的膜相关酪氨酸激酶。鉴定pp60c-src的靶膜可能会阐明c-src蛋白的功能。现有证据表明，pp60c-src与单一细胞类型内的不同膜相关，并且在不同细胞类型中具有不同的分布。我们的实验证明，在神经内分泌细胞系PC12中，pp60c-src靶向一种可分离且经生化鉴定的膜组分。发现c-src蛋白与突触小泡特异性相关，原因如下：(a) pp60c-src免疫荧光模式与突触小泡标记物突触素重叠；(b) 来自PC12而非成纤维细胞核后上清液的pp60c-src中有很大一部分（44%）在一个小泡组分中被回收；(c) 抗突触素细胞质结构域抗体免疫耗尽了该组分中所有的pp60c-src小泡，以及(d) 在对PC12突触小泡进行100倍纯化过程中，pp60c-src共同纯化。这些结果表明c-src蛋白在调节突触小泡功能中起作用。
