BINDING OF SIMPLE PEPTIDES, HORMONES, AND NEUROTRANSMITTERS BY CALMODULIN
BINDING OF SIMPLE PEPTIDES, HORMONES, AND NEUROTRANSMITTERS BY CALMODULIN
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DOI：
10.1021/bi00257a035
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发表时间：
1982-01-01
期刊：
影响因子：
2.9
通讯作者：
ANDERSON, SR
中科院分区：
文献类型：
--
作者：
MALENCIK, DA;ANDERSON, SR
猪钙调素荧光偶联物与5-（二甲氨基）-1-萘磺酰氯，是高度敏感的钙结合和蛋白质结合。除了固有肽荧光之外，该缀合物的荧光用于显示ACTH，β-内啡肽、胰高血糖素和P物质通过钙调蛋白进行Ca依赖性结合，竞争共同的结合位点。在0.85mM CaCl 2和0.2N KCl存在下，pH 7.3，25 ℃下测定Kd。C，范围为1.5 μ M至3.4 μ M。α- MSH、铃蟾肽和生长激素抑制素也结合，Kd在60 μ M和90 μ M之间。血管紧张素I和III、缓激肽、神经降压素、毒扁豆素、P物质八肽、胰岛素以及亮氨酸脑啡肽和蛋氨酸脑啡肽显示很少或没有结合。序列比较表明，结合钙调蛋白的肽以及含有结构上类似于cAMP依赖性蛋白激酶的识别序列和几种钙调蛋白结合蛋白中磷酸化丝氨酸残基周围序列的区域。修饰钙调素依赖蛋白中的钙调素结合位点是蛋白激酶的功能之一。Ca在钙调蛋白的肽结合中具有双重作用。具有pK apprx的Ca结合位点的占据4导致肽结合亲和力增加2倍。
A fluorescent conjugate of porcine calmodulin was prepared with 5-(dimethylamino)-1-naphthalene-sulfonyl chloride that is highly sensitive to both Ca binding and protein binding. The fluorescence of this conjugate in addition to the intrinsic peptide fluorescence was used to show that ACTH, .beta.-endorphin, glucagon, and substance P undergo Ca-dependent binding by calmodulin, with competition for common binding sites. The Kd determined in the presence of 0.85 mM CaCl2 and 0.2 N KCl, pH 7.3 at 25.degree. C, range from 1.5 .mu.M to 3.4 .mu.M. .alpha.-MSH, bombesin and somatostatin also bind, with Kd between 60 .mu.M and 90 .mu.M. Angiotensins I and III, bradykinin, neurotensin, physaelemin, substance P octapeptide, insulin, and Leu- and Met-enkephalin show little or no binding. Sequence comparisons show that the peptides that bind calmodulin well contain regions structurally similar to the recognition sequence for the cAMP-dependent protein kinase and to the sequences surrounding phosphorylated serine residues in several calmodulin binding proteins. Modification of calmodulin binding sites in calmodulin-dependent proteins is one of the functions of protein kinase. Ca has a dual role in peptide binding by calmodulin. The occupation of Ca binding sites having a pK .apprx. 4 results in a 2-fold increase in peptide binding affinity.