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Retinoblastoma Protein

The retinoblastoma protein, also known as pRb or p105, is a tumor suppressor protein which is

named from a chidhood cancer where it was first discovered



pRb inhibits the cell cycle

becomes inactive when it is phosphorylated by protein cyclin-dependent kinases Cdk4 and Cdk2, unblocking and allowing the cell to pass the restriction point in order to progress from the G1 phase into the S phase of the cell cycle. Prior to this crutial step, the activation of Cdk4 and Cdk2 must occur through the synthesis and binding of cyclins D and E to Cdk4 and Cdk2, respectively, which form cyclin-cdk complexes.

Purves et al. Life The Science Of Biology 7E

"previous studies indicate that the HCV RNA-dependent RNA polymerase, nonstructural protein 5B (NS5B), forms a complex with the retinoblastoma tumor suppressor protein (pRb), targeting it for degradation, activating E2F-responsive promoters, and stimulating cellular proliferation....the abundance of pRb is strongly downregulated, and its normal nuclear localization altered to include a major cytoplasmic component..."


Structure-function analysis of the retinoblastoma tumor suppressor protein – is the whole a sum of its parts?

Human papillomavirus immortalization and transformation functions