Kumar N, Klausner R D, Weinstein J N, Blumenthal R, Flavin M
J Biol Chem. 1981 Jun 10;256(11):5886-9.
We have shown that soluble tubulin will bind to small unilamellar vesicles of dipalmitoyl phosphatidylcholine (Klausner, R. D., Kumar, N., Weinstein, J. N., Blumenthal, R., and Flavin, M. (1981) J. Biol. Chem. 256, 5879-5885). This association uniquely occurs at the lipid phase transition. The tubulin, when bound to the vesicles, displays an altered tryptophan fluorescence characterized by a 5-nm blue shift in the emission maximum and a 22% decrease in fluorescence intensity, when compared to soluble tubulin. Tryptophans in vesicle-bound tubulin are less accessible to the aqueous collisional quenchers, acrylamide and iodide, than in soluble tubulin. Circular dichroism studies reveal an increase in alpha-helical content of tubulin as a result of vesicle interaction. Proteolytic digestion by trypsin of vesicle bound tubulin is slower than of soluble tubulin. The beta subunit of tubulin is preferentially protected from trypsin by vesicle interaction. Furthermore, the pattern of tryptic cleavage products is altered by this interaction.
我们已证明可溶性微管蛋白会与二棕榈酰磷脂酰胆碱的小单层囊泡结合（克劳斯纳，R.D.，库马尔，N.，温斯坦，J.N.，布卢门撒尔，R.，以及弗拉文，M.（1981年）《生物化学杂志》256卷，5879 - 5885页）。这种结合独特地发生在脂质相变时。与可溶性微管蛋白相比，当微管蛋白与囊泡结合时，其色氨酸荧光发生改变，其特征为发射最大值出现5纳米的蓝移且荧光强度降低22%。与可溶性微管蛋白相比，囊泡结合的微管蛋白中的色氨酸对水性碰撞猝灭剂丙烯酰胺和碘化物的可及性更低。圆二色性研究表明，由于与囊泡相互作用，微管蛋白的α - 螺旋含量增加。胰蛋白酶对囊泡结合的微管蛋白的蛋白水解消化比可溶性微管蛋白慢。囊泡相互作用优先保护微管蛋白的β亚基免受胰蛋白酶作用。此外，这种相互作用会改变胰蛋白酶裂解产物的模式。
