Catch muscle of bivalve molluscs contains myosin- and twitchin-associated protein kinase phosphorylating myorod
Catch muscle of bivalve molluscs contains myosin- and twitchin-associated protein kinase phosphorylating myorod
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DOI：
10.1016/j.bbapap.2009.12.020
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发表时间：
2010-04-01
影响因子：
3.2
通讯作者：
Sobieszek, Apolinary
中科院分区：
文献类型：
--
作者：
Matusovsky, Oleg S.;Shelud'ko, Nikolay S.;Sobieszek, Apolinary
我们以前已经证明，myorod，软体动物的粗丝蛋白的未知功能，是磷酸化的脊椎动物平滑肌肌球蛋白轻链激酶（MLCK）的N-末端的独特区域。本研究的目的是澄清这种磷酸化是否可能发生在软体动物肌肉。我们检测到三种内源性激酶的软体动物捕捉肌肉，即，由tickin，肌球蛋白和myorod的表面粗丝蛋白的复合物。第一种激酶是蛋白激酶A，因为它被特异性抑制剂抑制;第二种激酶与肌颤蛋白和磷酸化的肌球蛋白在其N-末端的独特区域独立于Ca（2+）;第三种激酶与肌球蛋白和磷酸化的肌球蛋白以及两种蛋白的C-末端部分的肌球蛋白结合。肌球蛋白相关激酶被微摩尔浓度的钙离子抑制。这种酶可以通过色谱法从肌球蛋白中分离出来，而与tickin相关的激酶不能从tickin中分离出来。由于tickin具有MLCK样结构域，因此该结构域可能负责肌样蛋白磷酸化。肌球蛋白-肌球蛋白复合物中的肌球蛋白磷酸化增加肌球蛋白肌动蛋白激活的Mg（2+）-ATP酶活性。加在一起。这些结果表明，与捕获收缩的关键蛋白相关的激酶对myorod的磷酸化可能有助于软体动物平滑肌中myorod的功能活性。(C)2010 Elsevier B. V.保留所有权利。
We have shown previously that myorod, a molluscan thick filament protein of unknown function, is phosphorylated by vertebrate smooth myosin light chain kinase (MLCK) in N-terminal unique region. The aim of the present study was to clarify whether such phosphorylation may occur in molluscan muscles. We detected three kinases endogenous to molluscan catch muscle, namely, to the complex of surface thick filament proteins that consists of twitchin, myosin, and myorod. The first kinase was a protein kinase A because it was inhibited by a specific inhibitor; the second one was associated with twitchin and phosphorylated myorod at its N-terminal unique region independently of Ca(2+); and the third kinase was bound to myosin and phosphorylated myorod as well as myosin in the C-terminal part of both proteins. The myosin-associated kinase was inhibited by micromolar concentration of calcium ions. This enzyme could be separated from myosin by chromatography, whereas the kinase associated with twitchin could not be separated from twitchin. Since twitchin has a MLCK-like domain, it is possible that this domain was responsible for myorod phosphorylation. Phosphorylation of myorod within the twitchin-myosin-myorod complex increased the actin-activated Mg(2+)-ATPase activity of myosin. Taken together. these results indicate that phosphorylation of myorod by kinases associated with key proteins of catch contraction may contribute to the functional activity of myorod in molluscan smooth muscle. (C) 2010 Elsevier B.V. All rights reserved.