Blum H E, Pocinwong S, Fischer E H
Proc Natl Acad Sci U S A. 1974 Jun;71(6):2198-2202. doi: 10.1073/pnas.71.6.2198.
A phosphate-acceptor protein was isolated from the skeletal muscle of the Pacific dogfish (Squalus acanthias) displaying properties extremely similar to those of the parvalbumins, i.e., the low-molecular-weight, soluble, Ca-binding muscle proteins found in fish and amphibians. It has the same characteristic UV spectrum, strong affinity for calcium, and immunological crossreactivity with antibodies against homogeneous dogfish parvalbumin. Although it was isolated in three states of aggregation with molecular weights of about 350,000, 75,000, and 25,000, all species dissociate in Na dodecyl sulfate into subunits of 11,000 and 13,000 molecular weight. Furthermore, whereas no phosphorylation of parvalbumins could be demonstrated under any experimental conditions, the aggregated forms could be readily phosphorylated by a cyclic AMP-independent dogfish protein kinase, but not by phosphorylase kinase. One acid-stable and base-labile phosphate group was introduced per subunit which could be rapidly released by a dogfish protein phosphatase, but only very slowly if at all by phosphorylase phosphatase. It is speculated that this "phosphate-acceptor protein" might represent a physiologically active form of the parvalbumins.
从太平洋角鲨（棘鲨）的骨骼肌中分离出一种磷酸受体蛋白，其性质与小白蛋白极为相似，即鱼类和两栖动物体内发现的低分子量、可溶、能结合钙的肌肉蛋白。它具有相同的特征紫外光谱，对钙有很强的亲和力，并且与抗纯角鲨小白蛋白的抗体有免疫交叉反应。尽管它以三种聚集状态被分离出来，分子量分别约为350,000、75,000和25,000，但所有这些形式在十二烷基硫酸钠中都会解离成分子量为11,000和13,000的亚基。此外，在任何实验条件下都无法证明小白蛋白会发生磷酸化，但聚集形式的蛋白可被一种不依赖环磷酸腺苷的角鲨蛋白激酶轻易磷酸化，而不能被磷酸化酶激酶磷酸化。每个亚基引入了一个酸稳定、碱不稳定的磷酸基团，该基团可被角鲨蛋白磷酸酶迅速释放，但如果由磷酸化酶磷酸酶释放，则非常缓慢，甚至根本不会释放。据推测，这种“磷酸受体蛋白”可能代表了小白蛋白的一种生理活性形式。
