Korrodi-Gregório Luís, Margarida Lopes Ana, Esteves Sara L C, Afonso Sandra, Lemos de Matos Ana, Lissovsky Andrey A, da Cruz e Silva Odete A B, da Cruz e Silva Edgar F, Esteves Pedro José, Fardilha Margarida
Laboratory of Signal Transduction, Centre for Cell Biology, Health Sciences Department and Biology Department, University of Aveiro, Aveiro, Portugal.
PLoS One. 2013 Oct 10;8(10):e77236. doi: 10.1371/journal.pone.0077236. eCollection 2013.
T-complex testis expressed protein 1 domain containing 4 (TCTEX1D4) contains the canonical phosphoprotein phosphatase 1 (PPP1) binding motif, composed by the amino acid sequence RVSF. We identified and validated the binding of TCTEX1D4 to PPP1 and demonstrated that indeed this protein is a novel PPP1 interacting protein. Analyses of twenty-one mammalian species available in public databases and seven Lagomorpha sequences obtained in this work showed that the PPP1 binding motif 90RVSF93 is present in all of them and is flanked by a palindromic sequence, PLGS, except in three species of pikas (Ochotona princeps, O. dauurica and O. pusilla). Furthermore, for the Ochotona species an extra glycosylation site, motif 96NLS98, and the loss of the palindromic sequence were observed. Comparison with other lagomorphs suggests that this event happened before the Ochotona radiation. The dN/dS for the sequence region comprising the PPP1 binding motif and the flanking palindrome highly supports the hypothesis that for Ochotona species this region has been evolving under positive selection. In addition, mutational screening shows that the ability of pikas TCTEX1D4 to bind to PPP1 is maintained, although the PPP1 binding motif is disrupted, and the N- and C-terminal surrounding residues are also abrogated. These observations suggest pika as an ideal model to study novel PPP1 complexes regulatory mechanisms.
含T-复合体睾丸表达蛋白1结构域4（TCTEX1D4）包含由氨基酸序列RVSF组成的典型蛋白磷酸酶1（PPP1）结合基序。我们鉴定并验证了TCTEX1D4与PPP1的结合，并证明该蛋白确实是一种新型的PPP1相互作用蛋白。对公共数据库中21种哺乳动物物种以及本研究中获得的7种兔形目序列的分析表明，PPP1结合基序90RVSF93在所有物种中均存在，并且除了三种鼠兔（高原鼠兔、达乌尔鼠兔和藏鼠兔）外，其两侧均有回文序列PLGS。此外，对于鼠兔属物种，还观察到一个额外的糖基化位点，基序96NLS98，以及回文序列的缺失。与其他兔形目动物的比较表明，这一事件发生在鼠兔辐射之前。包含PPP1结合基序和侧翼回文序列的序列区域的dN/dS高度支持以下假设：对于鼠兔属物种，该区域一直在正选择下进化。此外，突变筛选表明，尽管PPP1结合基序被破坏，且N端和C端周围的残基也被消除，但鼠兔TCTEX1D4与PPP1结合的能力得以维持。这些观察结果表明，鼠兔是研究新型PPP1复合体调控机制的理想模型。
