Editors' ChoiceCell Division

Cyclin into S Phase

Science's STKE  02 Nov 2004:
Vol. 2004, Issue 257, pp. tw397
DOI: 10.1126/stke.2572004tw397

Cyclin E functions as the activating subunit of the cyclin-dependent kinase 2 complex, which regulates the initiation of DNA synthesis (S phase) in proliferating cells. However, the phenotypes of cyclin E knockout mice are not identical to those of Cdk2 knockout mice, and so cyclin E may have other functions independent of its interaction with Cdk2. Matsumoto and Maller report the identification of one such function. Cyclin E was localized to the centrosome through a centrosomal localization signal (CLS), a 20-amino acid portion of the molecule. Expression of a CLS peptide that competes with the endogenous protein for binding to the centrosome, or expression of full-length cyclin E with a mutated CLS, inhibited the effect of cyclin E on DNA synthesis. Mutations that block interaction of cyclin E with Cdk2, however, did not hinder cyclin E's ability to promote DNA synthesis.

Y. Matsumoto, J. L. Maller, A centrosomal localization signal in cyclin E required for Cdk2-independent S phase entry. Science 306, 885-888 (2004). [Abstract] [Full Text]