Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Megakaryocytes are unique haemopoietic cells which undergo DNA replication, giving rise to polyploid cells. However, little is known about the mechanism of megakaryocytic polyploidization. To address this issue, we used the human megakaryocytic cell line Meg-J. In the presence of K-252a (an indolocarbasole derivative), Meg-J cells stopped proliferation and exhibited additional megakaryocytic features, including morphological changes, polyploidization, and increases in the levels of surface expression of platelet glycoprotein (GP) IIb/IIa and GPIb. Thrombopoietin (TPO) promoted the K-2 52a-induced polyploidization and megakaryocytic differentiation. In the process of K-252a-induced polyploidization, levels of expression of both cdc2 and cyclin B1 were elevated transiently and subsequently decreased. This suggested that the polyploidization process in Meg-J cells was at least in part associated with a transient elevation and subsequent decrease in the expression of cdc2/cyclin B1 complex, a critical kinase involved in G2/M cell cycle transition.
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PMID:K-252a-induced polyploidization and differentiation of a human megakaryocytic cell line, Meg-J: transient elevation and subsequent suppression of cyclin B1 and cdc2 expression in the process of polyploidization. 972 12

Protein phosphorylation is the mediator of many important cellular processes of signal transduction and cell regulation. Phosphorylation often occurs on multiple sites within a single protein, whereby the results of individual phosphorylations are not well defined. This is partially due to the lack of tools for analyzing specific phosphorylation states in a quantitative manner. We have developed a high-throughput, rapid, and quantitative method for the determination of the phosphorylation status of peptides and, more importantly, native protein substrates of kinases using a competitive fluorescence-based approach. We have applied our method to measuring the phosphorylation activity of the Wee1 and Myt1 kinases. Our technique allows one to monitor the bis-phosphorylation status of the Cdk2 protein using an antibody specific for bis-phosphorylated Cdk2 and a fluorescently labeled bis-phosphorylated Cdk2 peptide. We have used this assay to screen a library of 16 general kinase inhibitors against Wee1 and Myt1 activity. None of the inhibitors inhibited Wee1, but both staurosporine and K-252a inhibited Myt1, with IC(50) values of 9.2+/-3.6 and 4.0+/-1.3 microM, respectively.
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PMID:A fluorescence polarization assay for native protein substrates of kinases. 1269 25

Somatic polyploidy of species-specific and tissue-specific degrees occurs in almost all plant species studied so far, but nearly nothing is known about the control mechanisms switching the mitotic cycle to an endoreduplication cycle. In order to search for a possible role of the cdc2 kinase, cell suspension cultures of the Runner bean, Phaseolus coccineus (Leguminosae) were treated with K-252a, an inhibitor of protein kinase activity. The treatment resulted in continuous cell cycles without mitosis, and hence induced polyploidy levels up to 2048C. It is, therefore, suggested that phosphorylation of a protein kinase, probably of the cell cycle-important p34(cdc2) type, is involved in the control of endoreduplication.
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PMID:Induction of high polyploidy in Phaseolus cell cultures by the protein kinase inhibitor, K-252a. 2419 56