Aubert-Foucher E, Deléage G, Font B
LBTM-CNRS, Université Claude Bernard Lyon I, Villeurbanne, France.
Biochem Int. 1990 Dec;22(5):821-7.
Synapsin I plays an important role in the regulation of neurotransmitter release, since it binds to synaptic vesicles and to the cytoskeleton, and it bundles F-actin and microtubules. We have previously shown by tryptic digestion of synapsin I that a 44 kDa fragment contains a binding site for polymerized tubulin. In the present experiments, we test whether synapsin I and microtubule-associated proteins (MAPs) have the same or a different binding site on tubulin molecules. Our results show that heat stable MAPs do not compete with synapsin I for binding to taxol tubulin. In addition, subtilisin digestion of tubulin, which suppresses MAPs binding, does not abolish synapsin I cosedimentation with taxol tubulin. Thus, our results strongly suggest that synapsin I (as reported for kinesin) does not bind to the 4 kDa subtilisin digested C-terminal part of the tubulin molecule.
突触素I在神经递质释放的调节中起重要作用，因为它与突触小泡和细胞骨架结合，并能将F-肌动蛋白和微管捆绑在一起。我们之前通过对突触素I进行胰蛋白酶消化表明，一个44 kDa的片段含有与聚合微管蛋白的结合位点。在本实验中，我们测试突触素I和微管相关蛋白（MAPs）在微管蛋白分子上是否具有相同或不同的结合位点。我们的结果表明，热稳定的MAPs不会与突触素I竞争结合紫杉醇微管蛋白。此外，抑制MAPs结合的微管蛋白枯草杆菌蛋白酶消化不会消除突触素I与紫杉醇微管蛋白的共沉降。因此，我们的结果有力地表明，突触素I（如驱动蛋白的报道）不与微管蛋白分子经枯草杆菌蛋白酶消化的4 kDa C末端部分结合。
