MOLECULAR-CLONING OF A 2ND FORM OF RAC PROTEIN-KINASE
MOLECULAR-CLONING OF A 2ND FORM OF RAC PROTEIN-KINASE
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DOI：
10.1091/mbc.2.12.1001
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发表时间：
1991-12-01
期刊：
影响因子：
--
通讯作者：
HEMMINGS, BA
中科院分区：
文献类型：
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作者：
JONES, PF;JAKUBOWICZ, T;HEMMINGS, BA
最近已从源自人细胞系MCF-7和W138的cDNA文库中鉴定并克隆了一种新的丝氨酸/苏氨酸蛋白激酶（称为rac-PK）。这种蛋白激酶的第二种形式，称为 rac 蛋白激酶-β，已从源自相同细胞系的 cDNA 中鉴定出来。这两种密切相关的形式显示出 90% 的同源性，尽管与 α 形式相比，预测 M(r) 60 200 的 β 形式具有 40 个氨基酸的羧基末端延伸。该延伸具有高丝氨酸含量，最后 30 个氨基酸中有 11 个丝氨酸残基。体外翻译和细菌表达均表明该蛋白质的β型比α型大约5000 Da。 rac 蛋白激酶-β 由 3.4-kb 转录物编码，α 型由 3.2-kb mRNA 编码。使用基因特异性探针，在分析的所有细胞类型中均检测到两种转录物，尽管两种形式的表达水平不同。 rac 蛋白激酶-β 的催化结构域与蛋白激酶 C 和环 AMP 依赖性蛋白激酶家族均表现出高度同源性，因此 rac 蛋白激酶似乎代表了第二信使丝氨酸/苏氨酸蛋白激酶的新亚家族。
A novel serine/threonine protein kinase (termed rac-PK) has recently been identified and cloned from cDNA libraries derived from the human cell lines MCF-7 and Wl38. A second form of this protein kinase, termed rac protein kinase-beta, has been identified from cDNAs derived from the same cell lines. These two closely related forms show 90% homology, although the beta-form with a predicted M(r) 60 200 has a carboxyl terminal extension of 40 amino acids in comparison to the alpha-form. This extension has a high serine content with 11 serine residues in the last 30 amino acids. The beta-form of the protein has been shown by both in vitro translation and bacterial expression to be approximately 5000 Da larger than the alpha-form. rac protein kinase-beta is encoded by a 3.4-kb transcript and the alpha-form is encoded by a 3.2-kb mRNA. Using gene-specific probes both transcripts were detected in all cell types analyzed, although levels of expression were different for the two forms. The catalytic domain of rac protein kinase-beta shows a high degree of homology to both the protein kinase C and cyclic AMP-dependent protein kinase families, and hence rac protein kinases appear to represent a new subfamily of the second messenger serine/threonine protein kinases.