Regulation of the ubiquitin-conjugating enzyme hHR6A by CDK-mediated phosphorylation.
EMBO J
; 21(8): 2009-18, 2002 Apr 15.
Article
em En
| MEDLINE
| ID: mdl-11953320
ABSTRACT
Cell cycle progression in eukaryotes is mediated by phosphorylation of protein substrates by the cyclin-dependent kinases (CDKs). We screened a cDNA library by solid-phase phosphorylation and isolated hHR6A as a CDK2 substrate. hHR6A is the human homologue of the product of the Saccharomyces cerevisiae RAD6/UBC2 gene, a member of the family of ubiquitin-conjugating enzymes. hHR6A is phosphorylated in vitro by CDK-1 and -2 on Ser120, a residue conserved in all hHR6A homologues, resulting in a 4-fold increase in its ubiquitin-conjugating activity. In vivo, hHR6A phosphorylation peaks during the G2/M phase of cell cycle transition, with a concomitant increase in histone H2B ubiquitylation. Mutation of Ser120 to threonine or alanine abolished hHR6A activity, while mutation to aspartate to mimic phosphorylated serine increased hHR6A activity 3-fold. Genetic complementation studies in S.cerevisiae demonstrated that hHR6A Ser120 is critical for cellular proliferation. This is the first study to demonstrate regulation of UBC function by phosphorylation on a conserved residue and suggests that CDK-mediated phosphorylation of hHR6A is an important regulatory event in the control of cell cycle progression.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas Serina-Treonina Quinases
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Quinases Ciclina-Dependentes
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Ciclina A
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Proteínas de Saccharomyces cerevisiae
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Ubiquitina
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Quinases relacionadas a CDC2 e CDC28
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Ligases
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article