ISSN:
0730-2312
Keywords:
cyclin-dependent kinase
;
cell cycle
;
serine-threonine kinase
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Cyclin-dependent kinases (cdks) are a family of proteins whose function plays a critical role in cell cycle traverse. Transforming growth factor-β1 (TGF-β1) is a potent growth inhibitor of epithelial cells. Since cdks have been suggested as possible biochemical markers for TGF-β growth inhibition, we investigated the effect of TGF-β1 on cdc2 and cdk2 in a normal mouse mammary epithelial cell line (MME) and a TGF-β-resistant MME cell line (BG18.2). TGF-β1 decreases newly synthesized cdc2 protein levels within 6 h after addition. Coincident with this decrease in newly synthesized cdc2 protein was a marked reduction in its ability to phosphorylate histone H1. This decrease in kinase activity is not due to a change in steady-state levels of cdc2 protein, since mRNA and total protein levels of cdc2 are not reduced until 12 h after TGF-β1 addition. This suggests that the kinase activity of cdc2 is dependent on newly synthesized cdc2 protien. Moreover, the protein synthesis of another cyclin-dependent kinase, cdk2, is not effected by TGF-β1 addition, but its kinase activity is substantially reduced. Thus, it appears that TGF-β decreases the kinase activity of both cdc2 and cdk2 by distinct mechanisms.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcb.240580415
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