Casein kinase I alpha and alpha L: alternative splicing-generated kinases exhibit different catalytic properties.
Casein kinase I alpha and alpha L: alternative splicing-generated kinases exhibit different catalytic properties.
复制标题
DOI：
10.1021/bi9614444
复制
发表时间：
1996-12
期刊：
影响因子：
2.9
通讯作者：
Jiren Zhang;S. Gross;M. Schroeder;R. Anderson
中科院分区：
文献类型：
--
作者：
Jiren Zhang;S. Gross;M. Schroeder;R. Anderson
酪蛋白激酶I(Casein Kinase I，CKI)是一个丝氨酸/苏氨酸蛋白激酶家族，广泛存在于目前研究的所有真核生物中。在此，我们克隆并在真核和原核系统中表达了大鼠肌动蛋白Iα和αL亚型。对CKIαL特有外显子两侧基因组DNA的分析表明，CKIα和CKIαL是由一个共同的前信使核糖核酸分子交替剪接而产生的。据我们所知，α-L亚型是已知的唯一在其催化区域内含有插入物的活性丝氨酸/苏氨酸激酶。用RT-PCR、免疫沉淀和Western blotting检测各剪接异构体的组织分布。这两种异构体在所有受试组织中都有表达，但表达水平不同。细菌表达的CKIα亚型是活性的，因此具有生化特征。CKIα和CKIαL蛋白被证明具有酪蛋白激酶I的催化特性。更重要的是，重组异构体蛋白与常见的CKI底物在结合和活性上存在差异。这些观察结果表明，插入在激酶结构域中的α-L调控底物动力学。这些动力学差异表明，CKIα和CKIαL可能发挥不同的生物学作用。
Casein kinase I (CKI) is a family of serine/threonine protein kinases found in all eukaryotes examined to date. Here, the rat CKI isoforms alpha and alpha L were cloned and expressed in both eukaryotic and prokaryotic systems. Characterization of the genomic DNA flanking the exon unique to CKI alpha L demonstrated that CKI alpha and CKI alpha L arise by the alternative splicing of a common pre-mRNA molecule. To the best of our knowledge, the alpha L isoform is the only known active serine/threonine kinase to contain an insert within its catalytic domain. Tissue distribution of each splicing isoform was examined by RT-PCR, immunoprecipitation, and Western blotting. Both isoforms were expressed in all tissues tested but at different levels. Bacterially expressed CKI alpha isoforms were active and therefore biochemically characterized. CKI alpha and CKI alpha L proteins were demonstrated to have casein kinase I catalytic properties. More importantly, the recombinant isoform proteins exhibited differences in binding and activity toward common CKI substrates. These observations demonstrate that the alpha L insert within the kinase domain modulates substrate kinetics. These kinetic differences suggest that CKI alpha and CKI alpha L may perform different biological roles.