کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1964978 | 1058641 | 2006 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Phosphorylation of the Pro-X-Thr-Pro site in phosphatase inhibitor-2 by cyclin-dependent protein kinase during M-phase of the cell cycle
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Protein phosphorylation serves as a primary mechanism for triggering events during mitosis and depends on coordinated regulation of kinases and phosphatases. Protein Ser-Thr phosphatase-1 (PP1) activity is essential for the metaphase to anaphase transition and the most ancient regulator of PP1 conserved from yeast to human is inhibitor-2 (I-2), an unstructured heat-stable protein. A unique sequence motif in I-2 from various species surrounds a phosphorylation site PXTP that can be phosphorylated in biochemical assays by GSK3, MAPK and CDK kinases. Here we used a phosphosite specific antibody to investigate the phosphorylation of I-2. We fractioned extracts from HeLa cells arrested with nocodazole and assayed for PXTP kinases using recombinant I-2. One major and two minor peaks of kinase activity were identified and the major peak contained both active MAPK and cdk1â·cyclinB1, confirmed by immunoblotting. Cells released from a double thymidine block synchronously progressed through mitosis and immunoblotting revealed transient phosphorylation of endogenous I-2 in cells only during mitosis, and corresponding phosphorylation of histone H3 (Ser10) and PP1 (Thr320). Activation of cdk1â·cyclinB1 was coincident with I-2 phosphorylation, but neither MAPK nor GSK3 were phosphorylated at this time, so we concluded that in living cells only cdk1â·cyclinB1 phosphorylated the PXTP site in I-2. Immunofluorescent staining of cells with the PXTP phosphosite antibody revealed highly specific staining of mitotic cells prior to anaphase, at which point the staining disappeared. Thus, phosphorylation of I-2 is catalyzed by cdk1â·cyclinB1 and staining with a specific antibody should prove useful as a selective marker of cells in the early stages of mitosis.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cellular Signalling - Volume 18, Issue 8, August 2006, Pages 1318-1326
Journal: Cellular Signalling - Volume 18, Issue 8, August 2006, Pages 1318-1326
نویسندگان
Mingguang Li, Bjarki Stefansson, Weiping Wang, Erik M. Schaefer, David L. Brautigan,