Ngai P K, Carruthers C A, Walsh M P
Biochem J. 1984 Mar 15;218(3):863-70. doi: 10.1042/bj2180863.
A simple and rapid procedure for the purification of the native form of chicken gizzard myosin light-chain kinase (Mr 136000) is described which eliminates problems of proteolysis previously encountered. During this procedure, a calmodulin-binding protein of Mr 141000, which previously co-purified with the myosin light-chain kinase, is removed and shown to be a distinct protein on the basis of lack of kinase activity, different chymotryptic peptide maps, lack of cross-reactivity with a monoclonal antibody to turkey gizzard myosin light-chain kinase, and lack of phosphorylation by the purified catalytic subunit of cyclic AMP-dependent protein kinase. This Mr-141000 calmodulin-binding protein is identified as caldesmon on the basis of Ca2+-dependent interaction with calmodulin, subunit Mr, Ca2+-independent interaction with skeletal-muscle F-actin, Ca2+-dependent competition between calmodulin and F-actin for caldesmon, and tissue content.
本文描述了一种简单快速的方法来纯化天然形式的鸡砂囊肌球蛋白轻链激酶（分子量136000），该方法解决了以前遇到的蛋白水解问题。在此过程中，一种分子量为141000的钙调蛋白结合蛋白被去除，该蛋白以前与肌球蛋白轻链激酶共纯化，基于缺乏激酶活性、不同的胰凝乳蛋白酶肽图谱、与抗火鸡砂囊肌球蛋白轻链激酶单克隆抗体缺乏交叉反应以及缺乏环磷酸腺苷依赖性蛋白激酶纯化催化亚基的磷酸化作用，表明它是一种独特的蛋白质。基于与钙调蛋白的钙依赖性相互作用、亚基分子量、与骨骼肌F-肌动蛋白的钙非依赖性相互作用、钙调蛋白和F-肌动蛋白对钙调蛋白的钙依赖性竞争以及组织含量，这种分子量为141000的钙调蛋白结合蛋白被鉴定为钙调蛋白。
