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A role for the p34cdc2 kinase and phosphatases in the regulation of phosphorylation and disassembly of lamin B2 during the cell cycle.

Lüscher, B and Brizuela, L and Beach, D and Eisenman, R N (1991) A role for the p34cdc2 kinase and phosphatases in the regulation of phosphorylation and disassembly of lamin B2 during the cell cycle. The EMBO journal, 10 (4). pp. 865-875. ISSN 0261-4189

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While the p34cdc2 kinase is considered to be a critical regulator of mitosis, its function has not yet been directly linked to one of the key events during the onset of mitosis: nuclear envelope breakdown. Here we show that a major structural protein of the nuclear envelope, lamin B2, is phosphorylated by p34cdc2. Results from two-dimensional phosphopeptide mapping experiments demonstrate that the p34cdc2-specific phosphopeptides represent both mitotic and interphase specific phosphorylations of lamin B2 and include the major interphase phosphorylation site. In mitotic cells we detected two distinct forms of lamin B2 which differ in electrophoretic mobility and in degree of phosphorylation. The phosphorylation pattern of lamin B2 generated in vitro by p34cdc2 was more closely related to the less phosphorylated mitotic lamin B2, suggesting that another kinase(s) in addition to p34cdc2 is involved in generating the mitotic phosphorylation pattern. In addition, we show that treatment of interphase cells with okadaic acid, a potent phosphatase inhibitor, leads to the acquisition of mitosis-specific phosphopeptides and can reversibly increase the detergent-solubility of lamin B2. However, the M-phase-like phosphorylation of lamin B2 in itself is not sufficient to induce its disassembly from the nuclear lamina suggesting that an additional event(s) besides phosphorylation is required.

Item Type: Article or Abstract
Additional Information: This article is freely available in PubMed Central. No URL exists at the journal website.
PubMed ID: 1849074
PMCID: PMC452727
Grant Numbers: PO1 CA 28151, GM39620
Keywords or MeSH Headings: Animals; CDC2 Protein Kinase/metabolism; Cell Cycle/drug effects; Cell Line; Ethers, Cyclic/pharmacology; Lamin Type B; Lamins; Nuclear Envelope/ultrastructure; Nuclear Proteins/metabolism; Okadaic Acid; Peptide Mapping; Phosphopeptides/isolation & purification; Phosphoric Monoester Hydrolases/metabolism; Phosphorylation;
Subjects: Molecules > Proteins > Enzymes
Cellular and Organismal Processes > Cell Physiology > Cell cycle
Molecules > Proteins > Cell cycle proteins
Depositing User: Library Staff
Date Deposited: 03 Dec 2008 21:27
Last Modified: 21 May 2010 22:53

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