Papoutsopoulou S, Nikolakaki E, Giannakouros T
Laboratory of Biochemistry, School of Chemistry, Aristotelian University of Thessaloniki, Thessaloniki, 54 006, Greece.
Biochem Biophys Res Commun. 1999 Feb 24;255(3):602-7. doi: 10.1006/bbrc.1999.0249.
Arginine/serine protein kinases constitute a novel class of enzymes that can modify arginine/serine (RS) dipeptide motifs. SR splicing factors that are essential for pre-mRNA splicing and the lamin B receptor (LBR), an integral protein of the inner nuclear membrane, are among the best characterized proteins that contain RS domains. Two SR Protein-specific Kinases, SRPK1 and SRPK2, have been shown to phosphorylate specifically the RS motifs of the SR family of splicing factors and play an important role in regulating both the spliceosome assembly and their intranuclear distribution, whereas an LBR-associated kinase, that specifically phosphorylates a stretch of RS repeats located at the NH2-terminal region of LBR, has been recently purified and characterized from turkey erythrocyte nuclear envelopes. Using synthetic peptides representing different regions of LBR and recombinant proteins produced in bacteria we now demonstrate that SRPK1 modifies LBR with similar kinetics and on the same sites as the LBR kinase, that are also phosphorylated in vivo. These data provide significant evidence for a new role of SRPK1 in addition to that of pre-mRNA splicing.
精氨酸/丝氨酸蛋白激酶构成了一类新型酶，可修饰精氨酸/丝氨酸（RS）二肽基序。SR剪接因子是前体mRNA剪接所必需的，层粘连蛋白B受体（LBR）是内核膜的一种整合蛋白，它们是含有RS结构域的最具特征的蛋白质之一。两种SR蛋白特异性激酶，即SRPK1和SRPK2，已被证明可特异性磷酸化剪接因子SR家族的RS基序，并在调节剪接体组装及其核内分布中发挥重要作用，而一种与LBR相关的激酶，可特异性磷酸化位于LBR NH2末端区域的一段RS重复序列，最近已从火鸡红细胞核膜中纯化并鉴定出来。使用代表LBR不同区域的合成肽和细菌中产生的重组蛋白，我们现在证明SRPK1以与LBR激酶相似的动力学和相同的位点修饰LBR，这些位点在体内也会被磷酸化。这些数据为SRPK1除了在前体mRNA剪接中的作用之外的新作用提供了重要证据。
