Côté G P, Albanesi J P, Ueno T, Hammer J A, Korn E D
J Biol Chem. 1985 Apr 25;260(8):4543-6.
A low-molecular-weight myosin has been purified 1500-fold from extracts of Dictyostelium discoideum, based on the increase in K+,EDTA-ATPase specific activity. The purified enzyme resembles the single-headed, low-molecular-weight myosins IA and IB from Acanthamoeba castellanii, and differs from the conventional two-headed, high-molecular-weight myosin previously isolated from Dictyostelium, in several ways. It has higher K+,EDTA-ATPase activity than Ca2+-ATPase activity; it has a native molecular mass of about 150,000 and a single heavy chain of about 117,000; the 117,000-dalton heavy chain is phosphorylated by Acanthamoeba myosin I heavy chain kinase; phosphorylation of its heavy chain enhances its actin-activated Mg2+-ATPase activity; and the 117,000-dalton heavy chain reacts with antibodies raised against the heavy chain of Acanthamoeba myosin IA. None of these properties is shared by the low-molecular-weight active fragment that can be produced by chymotryptic digestion of conventional Dictyostelium myosin. We conclude that Dictyostelium contains an enzyme of the myosin I type previously isolated only from Acanthamoeba.
基于K⁺、EDTA - ATP酶比活性的增加，一种低分子量肌球蛋白已从盘基网柄菌提取物中纯化了1500倍。纯化后的酶类似于来自卡氏棘阿米巴的单头低分子量肌球蛋白IA和IB，并且在几个方面不同于先前从盘基网柄菌中分离出的传统双头高分子量肌球蛋白。它的K⁺、EDTA - ATP酶活性高于Ca²⁺ - ATP酶活性；其天然分子量约为150,000，有一条约117,000的重链；117,000道尔顿的重链可被棘阿米巴肌球蛋白I重链激酶磷酸化；其重链的磷酸化增强了其肌动蛋白激活的Mg²⁺ - ATP酶活性；并且117,000道尔顿的重链与针对棘阿米巴肌球蛋白IA重链产生的抗体发生反应。这些特性没有一个与通过胰凝乳蛋白酶消化传统盘基网柄菌肌球蛋白产生的低分子量活性片段所共有。我们得出结论，盘基网柄菌含有一种先前仅从棘阿米巴分离出的肌球蛋白I型酶。
