Dephosphorylation of distinct sites in myosin light chain by two types of phosphatase in aortic smooth muscle.
Dephosphorylation of distinct sites in myosin light chain by two types of phosphatase in aortic smooth muscle.
复制标题
主动脉平滑肌中两种类型的磷酸酶对肌球蛋白轻链中不同位点的去磷酸化。
DOI：
10.1016/0167-4889(89)90080-3
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Bárány,K
中科院分区：
文献类型：
--
作者：
Erdödi,F;Rokolya,A;Bárány,M;Bárány,K
用肝素-琼脂糖层析法从主动脉平滑肌提取液中分离出两种肌球蛋白轻链磷酸酶。流动组分中的磷酸酶对肌动球蛋白的活性较低，表观分子质量为260 kDa，经乙醇处理后，凝胶过滤测得其催化亚基的表观分子质量为36-39 kDa。该磷酸酶优先去磷酸化磷酸化酶α亚基，其磷酸化磷酸酶活性不受肝素、抑制物-1和抑制物-2的抑制。肝素-琼脂糖凝胶保留的磷酸酶对肌动球蛋白有很高的活性，表观分子量为150 kDa，乙醇处理后产生一个催化亚基，表观分子量为39-42 kDa。它优先去磷酸化磷酸化酶β亚基，其磷酸化磷酸酶活性不受肝素、抑制物-1和抑制物-2的抑制。肌球蛋白轻链由肌球蛋白轻链激酶在多肽AB(Ser-P)和Cd(Thr-P)和/或蛋白激酶C在多肽E(Ser-P)和F(Thr.P)中被磷酸化，通过一维磷酸肽图确定。在分离的轻链和肌动球蛋白中，肝素-琼脂糖流动磷酸酶催化亚基优先去磷酸化多肽F，而不是多肽AB、CD和E。肝素-琼脂糖结合磷酸酶催化亚基能有效地去磷酸化分离的轻链上的所有位点，而对肌动球蛋白中E肽的去磷酸化效果较差。
Two types of myosin light chain phosphatase from aortic smooth muscle extract were separated by chromatography on heparin-agarose. The phosphatase which appeared in the flow-through fractions had low activity on actomyosin, its apparent molecular mass was 260 kDa and upon ethanol treatment it generated a catalytic subunit with an apparent molecular mass of 36–39 kDa as determined by gel filtration. This phosphatase preferentially dephosphorylated the α-subunit of phosphorylase kinase and its phosphorylase phosphatase activity was not inhibited by heparin, inhibitor-1 or inhibitor-2. The phosphatase retained by heparin-agarose had high activity on actomyosin, its apparent molecular mass was 150 kDa and upon ethanol treatment it generated a catalytic subunit with an apparent molecular mass of 39–42 kDa. It preferentially dephosphorylated the β-subunit of phosphorylase kinase and its phosphorylase phosphatase activity was not inhibited by heparin, inhibitor-1 or inhibitor-2. Myosin light chain was phosphorylated by myosin light chain kinase in peptides AB (Ser-P) and CD (Thr-P), and/or by protein kinase C in peptides E (Ser-P) and F (Thr.P) as determined by one-dimensional phosphopeptide mapping. The catalytic subunit of heparin-agarose flow-through phosphatase preferentially dephosphorylated peptide F over peptides AB, CD and E in both isolated light chain and actomyosin. The catalytic subunit of heparin-agarose bound phosphatase could effectively dephosphorylate all sites in isolated light chain, whereas it was less effective on dephosphorylation of peptide E in actomyosin.