Ribot H D, Eisenman E A, Kinsey W H
J Biol Chem. 1984 Apr 25;259(8):5333-8.
The sea urchin egg contains one or more tyrosine-specific protein kinase(s) which are active during the response of the egg to sperm fusion. Fertilization results in an 8-fold increase in the relative incorporation of [32P]orthophosphate into phosphotyrosine as compared to phosphoserine and phosphothreonine. Under defined in vitro conditions, plasma membranes from fertilized eggs incorporated 5-10-fold more phosphate into tyrosine than plasma membranes from unfertilized eggs. Analysis of the phosphorylated plasma membrane proteins by polyacrylamide gel electrophoresis demonstrated that at least four proteins were more actively phosphorylated in plasma membranes from fertilized eggs. Of these, a closely spaced doublet of approximately 120 kDa was found to contain phosphotyrosine. The properties of the egg tyrosine-specific kinase were studied using an artificial peptide substrate. The enzyme is membrane-bound and is enriched 8-fold in the egg plasma membrane. Enzyme activity in egg homogenates and plasma membranes increased 2- and 4-fold, respectively, as early as 20 min, post-insemination. These results suggest that the fertilization-dependent increase in tyrosine-specific protein kinase activity may play a role in the onset of embryonic development.
海胆卵含有一种或多种酪氨酸特异性蛋白激酶，这些激酶在卵对精子融合的反应过程中具有活性。与磷酸丝氨酸和磷酸苏氨酸相比，受精导致[32P]正磷酸盐相对掺入磷酸酪氨酸的量增加了8倍。在特定的体外条件下，受精卵的质膜比未受精卵的质膜将多5至10倍的磷酸盐掺入酪氨酸。通过聚丙烯酰胺凝胶电泳对磷酸化的质膜蛋白进行分析表明，至少有四种蛋白质在受精卵的质膜中被更活跃地磷酸化。其中，发现一对紧密相邻的约120 kDa的双条带含有磷酸酪氨酸。使用人工肽底物研究了卵酪氨酸特异性激酶的特性。该酶与膜结合，在卵质膜中富集了8倍。早在授精后20分钟，卵匀浆和质膜中的酶活性分别增加了2倍和4倍。这些结果表明，酪氨酸特异性蛋白激酶活性的受精依赖性增加可能在胚胎发育的起始过程中起作用。
