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Abstract：
Three members of the obscurin protein family that contain tandem kinase domains with important signaling functions for cardiac and striated muscles are the giant protein obscurin, its obscurin-associated kinase splice isoform, and the striated muscle enriched protein kinase (SPEG). While there is increasing evidence for the specific roles that each individual kinase domain plays in cross-striated muscles, their biology and regulation remains enigmatic. Our present study focuses on kinase domain 1 and the adjacent low sequence complexity inter-kinase domain linker in obscurin and SPEG. Using Phos-tag gels, we show that the linker in obscurin contains several phosphorylation sites, while the same region in SPEG remained unphosphorylated. Our homology modeling, mutational analysis and molecular docking demonstrate that kinase 1 in obscurin harbors all key amino acids important for its catalytic function and that actions of this domain result in autophosphorylation of the protein. Our bioinformatics analyses also assign a list of putative substrates for kinase domain 1 in obscurin and SPEG, based on the known and our newly proposed phosphorylation sites in muscle proteins, including obscurin itself.
摘要：
包含对心肌和横纹肌具有重要信号功能的串联激酶结构域的暗示蛋白家族的三个成员是巨大的蛋白暗示蛋白，其暗素相关激酶剪接同工型，和横纹肌富集蛋白激酶(SPEG)。虽然越来越多的证据表明每个激酶结构域在横纹肌中起着特殊的作用，他们的生物学和调控仍然是神秘的。我们目前的研究集中在obsccurin和SPEG中的激酶结构域1和相邻的低序列复杂性激酶结构域间接头。使用Phos标签凝胶，我们证明了暗布蛋白中的接头含有几个磷酸化位点，而SPEG中的相同区域仍未磷酸化。我们的同源性建模,突变分析和分子对接表明，obscurin中的激酶1具有对其催化功能重要的所有关键氨基酸，并且该结构域的作用导致蛋白质的自磷酸化。我们的生物信息学分析还为obsccurin和SPEG中的激酶结构域1指定了假定的底物列表，基于肌肉蛋白中已知的和我们新提出的磷酸化位点，包括暗箱本身。
