Max F. Perutz Laboratories, Department of Chromosome Biology, University of Vienna, Vienna, Austria.
Cell Cycle. 2013 Mar 15;12(6):884-8. doi: 10.4161/cc.24095. Epub 2013 Mar 5.
Although the sterile 20 (Ste20) serine/threonine protein kinase was originally identified as a component of the S. cerevisiae mating pathway, it has homologs in higher eukaryotes and is part of a larger family of Ste20-like kinases. Ste20-like kinases are involved in multiple cellular processes, such as cell growth, morphogenesis, apoptosis and immune response. Carrying out such a diverse array of biological functions requires numerous regulatory inputs and outputs in the form of protein-protein interactions and post-translational modifications. Hence, a thorough knowledge of Ste20-like kinase binding partners and phosphorylation sites will be essential for understanding the various roles of these kinases. Our recent study revealed that Schizosaccharomyces pombe Nak1 (a conserved member of the GC-kinase sub-family of Ste20-like kinases) is in a complex with the leucine-rich repeat-containing protein Sog2. Here, we show a novel and unexpected interaction between the Nak1-Sog2 kinase complex and Casein kinase 2 (Cka1, Ckb1 and Ckb2) using tandem-affinity purification followed by mass spectrometric analysis. In addition, we identify unique phosphosites on Nak1, Sog2 and the catalytic subunit of casein kinase 2, Cka1. Given the conserved nature of these kinases, we expect this work will shed light on the functions of these proteins both in yeast and higher eukaryotes.
虽然无菌 20（Ste20）丝氨酸/苏氨酸蛋白激酶最初被鉴定为酿酒酵母交配途径的一个组成部分，但它在高等真核生物中有同源物，是 Ste20 样激酶家族的一个组成部分。Ste20 样激酶参与多种细胞过程，如细胞生长、形态发生、细胞凋亡和免疫反应。要执行如此多样化的生物功能，需要通过蛋白质-蛋白质相互作用和翻译后修饰等形式来进行大量的调节输入和输出。因此，深入了解 Ste20 样激酶结合伴侣和磷酸化位点对于理解这些激酶的各种作用至关重要。我们最近的研究表明，裂殖酵母 Nak1（Ste20 样激酶 GC-激酶亚家族的保守成员）与富含亮氨酸重复的蛋白 Sog2 形成复合物。在这里，我们使用串联亲和纯化 followed by mass spectrometric analysis（串联亲和纯化 followed by mass spectrometric analysis）显示 Nak1-Sog2 激酶复合物与酪蛋白激酶 2（Cka1、Ckb1 和 Ckb2）之间存在一种新颖且出乎意料的相互作用。此外，我们还鉴定了 Nak1、Sog2 和酪蛋白激酶 2 的催化亚基 Cka1 上的独特磷酸化位点。鉴于这些激酶的保守性质，我们预计这项工作将阐明这些蛋白质在酵母和高等真核生物中的功能。
