Article Abstract:
LIM-kinase 1 (LIMK-1) phosphorylates cofilin, a vital protein that is needed for turnover of actin filaments. Furthermore, LIMK-1, but not an inactive form of the enzyme, can phosphorylate recombinant cofilin. These findings explain why overexpression of LIMK-1 produces an accumulation of excess actin filaments, while overexpression of a dominant-negative LIMK-1 restricts the accumulation of actin filaments. It is possible that a fall in LIMK-1 could explain the abnormally clustered and aligned neurons seen in the brains of patients with Williams syndrome.
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Article Abstract:
Crystal structure of cyclin dependent kinase (Cdk2), complexed with cyclinA and inhibitory subunit p27, reveals that p27 introduces extensive conformational changes in Cdk2 to inhibit its kinase activity. A short amino acid motif on p27 is inserted in the binding pocket on cyclinA. The Beta-turn segment in the carboxy-terminal region of p27 distorts the beta-sheet of the kinase, and the beta-strand segment of p27 displaces the carboxy-terminal segment of p27.
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Article Abstract:
Cyclin-dependent kinase 2 (CDK2) has a bi-lobate structure with a unique helix-loop segment adjacent to the enzyme's active site that interferes with ATP and protein substrate binding. It is part of a family of protein kinases regulating the eukaryotic cell cycle; activation of the CDKs at cell cycle stages seems to trigger the cell cycle's principal transitions. This study determines CDK2's crystal structure to 2.4 Angstroms.
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