Heierhorst J, Tang X, Lei J, Probst W C, Weiss K R, Kemp B E, Benian G M
St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
Eur J Biochem. 1996 Dec 15;242(3):454-9. doi: 10.1111/j.1432-1033.1996.454rr.x.
Myosin-associated giant protein kinases of the titin/witchin-like superfamily have previously been implicated in the regulation of muscle function, based on genetic and physiological studies. We find that recombinant constitutively active Caenorhabditis elegans and Aplysia twitchin kinase fragments differ in their catalytic activities and peptide-substrate specificities, as well as in their sensitivities to the naphthalene sulfonamide inhibitors 1-(5-chloronaphthalenesulfonyl)-1H-hexahydro-1,4-diazepine (ML-7) and 1-(5-iodonaphthalenesulfonyl)-1H-hexahydro-1,4-diazepine (ML-9). The constitutively active Aplysia twitchin kinase fragment has a remarkably high activity (Vmax > 100 mumol.min-1.mg-1) towards some substrate peptides. The autoinhibited forms of these twitchin kinases can be activated in a Ca(2+)-dependent manner by the dimeric form of the S100A1 protein (S100A1(2)). The twitchin kinase S100A1(2)-binding site can also bind Ca2+/calmodulin but neither kinase is activated by calmodulin. The data provide a functional basis for the ongoing crystallographic study of twitchin kinase fragments.
基于遗传学和生理学研究，肌联蛋白/类witchin超家族中与肌球蛋白相关的巨蛋白激酶先前被认为参与肌肉功能的调节。我们发现，重组的组成型活性秀丽隐杆线虫和海兔twitchin激酶片段在催化活性、肽底物特异性以及对萘磺酰胺抑制剂1-(5-氯萘磺酰基)-1H-六氢-1,4-二氮杂卓(ML-7)和1-(5-碘萘磺酰基)-1H-六氢-1,4-二氮杂卓(ML-9)的敏感性方面存在差异。组成型活性海兔twitchin激酶片段对某些底物肽具有非常高的活性(Vmax>100 μmol·min-1·mg-1)。这些twitchin激酶的自身抑制形式可被S100A1蛋白的二聚体形式(S100A1(2))以Ca(2+)依赖的方式激活。twitchin激酶S100A1(2)结合位点也可结合Ca2+/钙调蛋白，但两种激酶均不被钙调蛋白激活。这些数据为正在进行的twitchin激酶片段晶体学研究提供了功能基础。
