Cumulative Effect of Phosphorylation of pRB on Regulation of E2F Activity

AUTOR(ES)

Brown, Vivette D.

FONTE

American Society for Microbiology

RESUMO

The product of the retinoblastoma susceptibility gene, pRB, is a nuclear phosphoprotein that controls cell growth by binding to and suppressing the activities of transcription factors such as the E2F family. Transactivation activity is inhibited when E2F is bound to hypophosphorylated pRB and released when pRB is phosphorylated by cyclin-dependent kinases (CDKs). To determine which of 16 potential CDK phosphorylation sites regulated the pRB-E2F interaction, mutant pRB proteins produced by site-directed mutagenesis were tested for the ability to suppress E2F-mediated transcription in a reporter chloramphenicol acetyltransferase assay. Surprisingly, no one CDK site regulated the interaction of pRB with E2F when E2F was bound to DNA. Instead, disruption of transcriptional repression resulted from accumulation of phosphate groups on the RB molecule.

Documentos Relacionados

• Regulation of E2F through ubiquitin–proteasome-dependent degradation: Stabilization by the pRB tumor suppressor protein
• Active repression and E2F inhibition by pRB are biochemically distinguishable
• Bcl-2 Retards Cell Cycle Entry through p27Kip1, pRB Relative p130, and Altered E2F Regulation
• Analysis of promoter binding by the E2F and pRB families in vivo: distinct E2F proteins mediate activation and repression
• The B-Domain Lysine Patch of pRB Is Required for Binding to Large T Antigen and Release of E2F by Phosphorylation