Usami M, Takahashi A, Kadota K
Biochim Biophys Acta. 1984 Apr 24;798(3):306-12. doi: 10.1016/0304-4165(84)90103-x.
Coated vesicles prepared from bovine brains contained a protein kinase activity which catalyzed the phosphorylation of endogenous structural proteins, Mr 150 000, 120 000, 48 000 and 32 000. An endogenous protein, Mr 48 000 was most strongly phosphorylated by this kinase. This protein kinase also phosphorylated exogenous proteins, phosvitin intensely and casein slightly but not histone or protamine. The enzyme activity was independent of cyclic nucleotides or Ca2+/calmodulin. Mg2+ stimulated the kinase activity. Some divalent cations were substituted for Mg2+; the potency decreased in the order Mn2+, Mg2+, Co2+, Ca2+, Zn2+. Two separate subfractions, the outer coat and the inner vesicle (core), were prepared from coated vesicles by a urea treatment followed by sucrose density gradient centrifugation and dialysis. The kinase activity was found predominantly in the coat subfraction.
从牛脑制备的包被小泡含有一种蛋白激酶活性，它催化内源性结构蛋白（分子量分别为150000、120000、48000和32000）的磷酸化。一种分子量为48000的内源性蛋白被这种激酶磷酸化的程度最强。这种蛋白激酶也能磷酸化外源性蛋白，对卵黄高磷蛋白的磷酸化作用强烈，对酪蛋白的磷酸化作用较弱，但对组蛋白或鱼精蛋白则无磷酸化作用。该酶活性不依赖于环核苷酸或Ca2+/钙调蛋白。Mg2+能刺激激酶活性。可用一些二价阳离子替代Mg2+；其效力按Mn2+、Mg2+、Co2+、Ca2+、Zn2+的顺序降低。通过尿素处理，随后进行蔗糖密度梯度离心和透析，从包被小泡中制备出两个独立的亚组分，即外被和内小泡（核心）。激酶活性主要存在于外被亚组分中。
