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Molecular and Cellular Biology, December 1998, p. 7584-7589, Vol. 18, No. 12
Department of Molecular Biology, Scripps
Research Institute, La Jolla, California 92037,1
and
Department of Genetics and Howard Hughes Medical Institute,
Yale University School of Medicine, New Haven, Connecticut
065102
Received 10 June 1998/Returned for modification 13 August
1998/Accepted 21 August 1998
Cyclin E, a partner of the cyclin-dependent kinase Cdk2, has been
implicated in positive control of the G1/S phase
transition. Whereas degradation of cyclin E has been shown to be
exquisitely regulated by ubiquitination and proteasomal action, little
is known about posttranscriptional aspects of its biogenesis. In a
yeast-based screen designed to identify human proteins that interact
with human cyclin E, we identified components of the eukaryotic
cytosolic chaperonin CCT. We found that the endogenous CCT complex in
yeast was essential for the maturation of cyclin E in vivo. Under
conditions of impaired CCT function, cyclin E failed to accumulate.
Furthermore, newly translated cyclin E, both in vitro in reticulocyte
lysate and in vivo in human cells in culture, is efficiently bound and
processed by the CCT. In vitro, in the presence of ATP, the bound
protein is folded and released in order to become associated with Cdk2.
Thus, both the acquisition of the native state and turnover of cyclin E
involve ATP-dependent processes mediated by large oligomeric assemblies.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Maturation of Human Cyclin E Requires the Function
of Eukaryotic Chaperonin CCT
*
Corresponding author. Mailing address: Department of
Molecular Biology, MB7, Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037. Phone: (619) 784-9836. Fax: (619) 784-2781. E-mail: sreed{at}scripps.edu.
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