Kuroyanagi N, Onogi H, Wakabayashi T, Hagiwara M
Department of Anatomy, Nagoya University School of Medicine, Japan.
Biochem Biophys Res Commun. 1998 Jan 14;242(2):357-64. doi: 10.1006/bbrc.1997.7913.
SR-protein-specific kinase 1 (SRPK1) is first identified as a specific kinase for SR splicing factors. By RT-PCR of a conserved kinase domain, novel SR-protein-specific kinase clones were isolated from mouse brain. The cloned cDNAs encode a 106 kDa protein (648 amino acids, 92% identical to human SRPK1) and a 120 kDa protein (681 amino acids, 58% identical to human SRPK1). Therefore, they were designated mSRPK1 and mSRPK2, respectively. Northern blotting revealed the ubiquitous expression of mSRPK1 in all tissues examined and the tissue-specific expression of mSRPK2 in testis, lung, and brain. Both kinases phosphorylated SF2/ASF, a member of SR proteins in vitro and the phosphopeptide mappings were identical, indicating that these kinases phosphorylate the same site of SF2/ASF. Overexpression of mSRPK2 caused disassembly of cotransfected SF2/ASF and endogenous SC35. Our results indicate that SRPK family members may regulate the disassembly of the SR proteins in a tissue-specific manner.
SR蛋白特异性激酶1（SRPK1）最初被鉴定为SR剪接因子的特异性激酶。通过对保守激酶结构域进行逆转录聚合酶链反应（RT-PCR），从小鼠脑中分离出新型SR蛋白特异性激酶克隆。克隆的cDNA编码一种106 kDa的蛋白质（648个氨基酸，与人类SRPK1的同源性为92%）和一种120 kDa的蛋白质（681个氨基酸，与人类SRPK1的同源性为58%）。因此，它们分别被命名为mSRPK1和mSRPK2。Northern印迹分析显示，mSRPK1在所检测的所有组织中普遍表达，而mSRPK2在睾丸、肺和脑中呈组织特异性表达。两种激酶在体外均能磷酸化SR蛋白成员之一的SF2/ASF，且磷酸肽图谱相同，表明这些激酶磷酸化SF2/ASF的相同位点。mSRPK2的过表达导致共转染的SF2/ASF和内源性SC35解聚。我们的结果表明，SRPK家族成员可能以组织特异性方式调节SR蛋白的解聚。
