Purification and subunit structure of bovine brain modulator binding protein.
Purification and subunit structure of bovine brain modulator binding protein.
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牛脑调节剂结合蛋白的纯化和亚基结构。
DOI：
10.1016/s0021-9258(18)50726-2
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
J. H. Wang
中科院分区：
文献类型：
--
作者：
R. Sharma;R. Desai;D. Waisman;J. H. Wang
最近发现了一种蛋白质，它可以与Ca+依赖性调节蛋白结合，从而抑制Ca +-可激活的环核苷酸磷酸二酯酶，并将其命名为调节结合蛋白（Wang，JH，和Desai，R.（1977）J.Biol.Chem.252，4175-4183; Klee，CB和Krinks，MH（1978）Biochemistry 17，120-126）。该蛋白质从牛脑中纯化至接近同质。纯化过程主要基于该蛋白质与高酸性调节蛋白质的Ca '+依赖性缔合。纯化的调节剂结合蛋白显示为分子量为85，000的球状蛋白。它含有两个不同的亚基，亚基A和B，分子量分别约为60，000和14，500。亚基A/B的质量比确定为约2.3：1。根据这些结果，调节剂结合蛋白的亚基结构被建议为AB 2。在6 M尿素存在下，调节剂结合蛋白解离成其组成亚基，并且亚基A和B可在G-100 Sephadex柱上分离。分离的亚基A显示出对Ca-可激活的环核苷酸磷酸二酯酶的抑制活性。亚基B没有磷酸二酯酶抑制活性，也不影响亚基A在酶反应中的活性。这些结果表明，亚基A负责调节剂结合蛋白与调节剂蛋白的缔合。亚基B的功能目前尚不清楚。最初作为哺乳动物组织中环核苷酸磷酸二酯酶的激活蛋白而发现的Ca-依赖性调节蛋白（1 -8），最近发现其介导几种其它反应的Ca-激活。这些反应包括由脑腺苷酸环化酶（9）、红细胞膜（Ca ′/Mg*+）-ATP酶（10，11）、膜结合蛋白激酶（12）和对肌球蛋白轻链磷酸化具有有效活性的胞质蛋白激酶（13，14）催化的反应。此外，已显示与肌钙蛋白C（15-18）具有相当大的序列同源性的该蛋白质可在体外肌动蛋白ATP酶（19，20）调节中替代后者蛋白质。
A protein which can associate with the Ca”-dependent modulator protein resulting in the inhibition of the Ca’+-activatable cyclic nucleotide phosphodiesterase has been discovered recently and designated as modulator binding protein (Wang, JH, and Desai, R.(1977) J. Biol. Chem. 252, 4175-4183; Klee, CB, and Krinks, MH (1978) Biochemistry 17, 120-126). This protein is purified from bovine brain to near homogeneity. The purification procedure is based mainly on the Ca’+-dependent association of this protein with the highly acidic modulator protein. The purified modulator binding protein is shown to be a globular protein of molecular weight 85,000. It contains two distinct subunits, subunits A and B, of molecular weights about 60,000 and 14,500, respectively. The mass ratio of subunits A/B is determined to be about 2.3: 1. From these results, the subunit structure of modulator binding protein is suggested to be AB2. In the presence of 6 M urea, modulator binding protein dissociates into its constituent subunits, and subunits A and B can be separated on a G-100 Sephadex column. The isolated subunit A exhibits inhibitory activity against the Ca”-activatable cyclic nucleotide phosphodiesterase. Subunit B has no phosphodiesterase inhibiting activity, nor does it affect the activity of subunit A in the enzyme reaction. These results suggest that subunit A is responsible for the association of modulator binding protein to the modulator protein. The function of subunit B is not known at present.The Ca”-dependent modulator protein, which was originally discovered as an activator protein of cyclic nucleotide phosphodiesterase in mammalian tissues (l-8), has recently been found to mediate the Ca”+ activation of several other reactions. These include reactions catalyzed by a brain adenylate cyclase (9), erythrocyte membrane (Ca’/Mg*+)-ATPase (10, ll), a membrane-bound protein kinase (12), and a cytosolic protein kinase which has potent activity toward myosin light chain phosphorylation(13, 14). In addition, this protein which has been shown to possess considerable sequence homology with troponin C (15-18) can substitute for the latter protein in the actomyosine ATPase (19, 20) regulation in vitro.