A cholera toxin-sensitive G-protein stimulates exocytosis in sea urchin eggs.
A cholera toxin-sensitive G-protein stimulates exocytosis in sea urchin eggs.
复制标题
霍乱毒素敏感的 G 蛋白会刺激海胆卵的胞吐作用。
DOI：
10.1016/0012-1606(87)90260-0
复制
发表时间：
1987
影响因子：
2.7
通讯作者：
Primakoff,P
中科院分区：
文献类型：
--
作者：
Turner,PR;Jaffe,LA;Primakoff,P
为了鉴定海胆卵中的鸟嘌呤核苷酸结合蛋白（g -protein）并探讨其在受精信号转导中的作用，我们利用霍乱毒素（CTX）和百日破毒素（PTX）催化g -蛋白的特异性adp核糖基化。用异种飞蝇卵制备细胞表面复合物，由质膜和粘附的皮质囊泡组成，并用32p标记的NAD在CTX或PTX存在下孵育。CTX催化47-kDa多肽的adp -核糖基化，而PTX催化40-kDa多肽的adp -核糖基化。将~ 30 μg/ml全CTX或~ 20 μg/ml CTX亚基A微量注射到完整卵子中，可引起皮质小泡的胞吐。然而，如果鸡蛋先注射EGTA (0.6-1.4 mM)，注射CTX不会引起胞吐。鸡蛋注射了0.8-2.8 mMcAMP或1.0-4.0 mMcAMP的腺苷3 ':5 ' -单磷硫酸环sp -异构体（cAMP- s）， cAMP的抗水解类似物，没有发生胞外分泌。这些结果表明，ctx敏感的g蛋白参与调节海胆卵皮质囊泡的Ca2+释放和胞吐。
To identify guanine nucleotide binding proteins (G-proteins) in sea urchin eggs and to investigate their role in signal transduction at fertilization, we used cholera toxin (CTX) and pertussis toxin (PTX), which catalyze the specific ADP-ribosylation of G-proteins. Cell surface complex, consisting of plasma membranes and adhering cortical vesicles, was prepared from eggs ofLytechinus variegatusand incubated with32P-labeled NAD in the presence of CTX or PTX. CTX catalyzed the ADP-ribosylation of a 47-kDa polypeptide, whereas PTX catalyzed the ADP-ribosylation of a 40-kDa polypeptide. Microinjection of ∼30 μg/ml whole CTX or ∼20 μg/ml CTX subunit A into intact eggs caused exocytosis of cortical vesicles. However, if the eggs were first injected with EGTA (0.6–1.4 mM), injection of CTX did not cause exocytosis. Eggs injected with 0.8–2.8 mMcAMP or 1.0–4.0 mMadenosine 3′:5′-monophosphothioate cyclic Sp-isomer (cAMP-S), a hydrolysis-resistant analog of cAMP, did not undergo exocytosis. These results suggest that a CTX-sensitive G-protein is involved in regulating Ca2+release and exocytosis of cortical vesicles in sea urchin eggs.