Sano Kiyoshi
Developmental Biology Laboratory, Department of Plastic Surgery, Kitasato University School of Medicine, Sagamihara, Kanagawa 228, Japan.
Dev Growth Differ. 1985;27(3):263-275. doi: 10.1111/j.1440-169X.1985.00263.x.
A burst of protein phosphorylation and an appearance of maturation-promoting factor have been reported to occur shortly before germinal vesicle (nucleus) breakdown (GVBD) in 1-methyladenine-induced oocyte maturation of starfish. To detect if a protein kinase is activated before GVBD, protein kinase activity was compared in maturing oocytes which were just undergoing GVBD and immature oocytes of Asterina pectinifera. The oocytes were homogenized in a buffer modified from that used for extracting amphibian maturation-promoting factor. When the supernatant protein of homogenized immature oocytes was used as a substrate, protein kinase activity in the supernatant of the maturing oocytes was 7-fold higher than that of immature oocytes. The protein kinase in the supernatant of the maturing oocytes showed a high substrate specificity for histone H1 among the exogenous substrates examined, and the activity of the maturing oocytes for histone H1 was 6- to 7-fold higher than that of immature oocytes. The protein kinase detected in the maturing oocytes was very labile and was inhibited neither by ethylene glycol bis(β-aminoethyl ether)N, N, N', N'-tetraacetic acid nor by the heat-stable inhibitor protein of cyclic AMP-dependent protein kinase. These results indicate that a calcium- and cyclic AMP-independent, labile "maturation-specific protein kinase" appeared before GVBD in maturing oocytes, and suggest its participation in the phosphorylation burst in vivo. The possible correlation of this kinase with maturation-promoting factor and chromosome condensation was discussed.
据报道，在海星1-甲基腺嘌呤诱导的卵母细胞成熟过程中，在生发泡（细胞核）破裂（GVBD）前不久会发生一阵蛋白质磷酸化并出现成熟促进因子。为了检测在GVBD之前是否有蛋白激酶被激活，比较了刚经历GVBD的成熟卵母细胞和栉孔扇贝未成熟卵母细胞中的蛋白激酶活性。卵母细胞在一种从用于提取两栖类成熟促进因子的缓冲液改良而来的缓冲液中匀浆。当以匀浆的未成熟卵母细胞的上清蛋白作为底物时，成熟卵母细胞上清中的蛋白激酶活性比未成熟卵母细胞高7倍。在检测的外源底物中，成熟卵母细胞上清中的蛋白激酶对组蛋白H1表现出高底物特异性，成熟卵母细胞对组蛋白H1的活性比未成熟卵母细胞高6至7倍。在成熟卵母细胞中检测到的蛋白激酶非常不稳定，既不受乙二醇双（β-氨基乙基醚）N，N，N'，N'-四乙酸抑制，也不受环磷酸腺苷依赖性蛋白激酶的热稳定抑制蛋白抑制。这些结果表明，在成熟卵母细胞的GVBD之前出现了一种不依赖钙和环磷酸腺苷的、不稳定的“成熟特异性蛋白激酶”，并提示其参与体内的磷酸化爆发。讨论了这种激酶与成熟促进因子和染色体凝聚的可能相关性。
