Mammalian mediator subunit mMED8 is an Elongin BC-interacting protein that can assemble with Cul2 and Rbx1 to reconstitute a ubiquitin ligase

摘要

The heterodimeric Elongin BC complex has been shown to interact in vitro and in cells with a conserved BC-box motif found in an increasing number of proteins including RNA polymerase II elon- gation factor Elongin A, suppressor of cytokine signaling (SOCS)- box proteins, and the von Hippel-Lindau tumor suppressor protein. Recently, the Elongin BC complex was found to function as an adaptor that links these BC-box proteins to a module composed of Cullin family members Cul2 or Cul5 and RING-H2 finger protein Rbx1 to reconstitute a family of E3 ubiquitin ligases that activate ubiquitylation by the E2 ubiquitin-conjugating enzyme Ubc5.