In vitro ubiquitination of cyclin D1 by ROC1–CUL1 and ROC1–CUL3

摘要: Overexpression of cyclin D1 has been implicated in a variety tumors, such as breast cancers, gastrointestinal cancers and lymphomas. Both gene amplification protein degradation mediated by ubiquitin (Ub)-dependent proteolysis regulate the abundance D1. Here we report that ROC1 interacted with all three D type cyclins vivo but did not bind to other tested. The ROC1–CUL1 ROC1–CUL3, ROC1–CUL2, –CUL3 –CUL4, immunocomplexes promoted polyubiquitination bacterially purified vitro. RING finger mutations eliminated Ub ligase activity toward In cases ubiquitination was accompanied autoubiquitination cullins. results suggest involvement ROC1–cullin ligases potential mechanism whereby cullin subunit is ubiquitinated itself while ubiquitinating substrate.