Gallagher P J, Herring B P, Griffin S A, Stull J T
Department of Physiology, University of Texas Southwestern Medical Center, Dallas 75235-9040.
J Biol Chem. 1991 Dec 15;266(35):23936-44.
A 5.6-kilobase cDNA clone has been isolated which includes the entire coding region for the myosin light chain kinase from rabbit uterine tissue. This cDNA, expressed in COS cells, encodes a Ca2+/calmodulin-dependent protein kinase with catalytic properties similar to other purified smooth muscle myosin light chain kinases. A module (TLKPVGNIKPAE), repeated sequentially 15 times, has been identified near the N terminus of this smooth muscle kinase. It is not present in chicken gizzard or rabbit skeletal muscle myosin light chain kinases. This repeat module and a subrepeat (K P A/V) are similar in amino acid content to repeated motifs present in other proteins, some of which have been shown to associate with chromatin structures. Immunoblot analysis after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, used to compare myosin light chain kinase present in rabbit, bovine, and chicken smooth and nonmuscle tissues, showed that within each species both tissue types have myosin light chain kinases with indistinguishable molecular masses. These data suggest that myosin light chain kinases present in smooth and nonmuscle tissues are the same protein.
已分离出一个5.6千碱基的cDNA克隆，它包含来自兔子宫组织的肌球蛋白轻链激酶的完整编码区。该cDNA在COS细胞中表达，编码一种Ca2+/钙调蛋白依赖性蛋白激酶，其催化特性与其他纯化的平滑肌肌球蛋白轻链激酶相似。在这种平滑肌激酶的N端附近发现了一个模块（TLKPVGNIKPAE），它依次重复了15次。鸡胗或兔骨骼肌肌球蛋白轻链激酶中不存在该模块。这个重复模块和一个亚重复序列（K P A/V）在氨基酸含量上与其他蛋白质中存在的重复基序相似，其中一些已被证明与染色质结构相关。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳后的免疫印迹分析用于比较兔、牛和鸡的平滑肌和非肌肉组织中存在的肌球蛋白轻链激酶，结果表明，在每个物种中，两种组织类型都有分子量难以区分的肌球蛋白轻链激酶。这些数据表明，平滑肌和非肌肉组织中存在的肌球蛋白轻链激酶是同一种蛋白质。
