Elongin BC Complex
The mammalian elongin BC complex is a heterodimer, composed of the 118 amino acid ubiquitin-like elongin B protein and the 112 amino acid elongin C protein. The elongin BC complex interacts through a short, degenerate BC-box motif with multiple proteins, including the transcription factor elongin A, the von Hippel–Lindau (VHL) tumor suppressor protein, and members of the SOCS-box protein family.
The elongin B and C proteins were initially identified as positive regulatory subunits of the three-subunit elongin complex, which is one of several transcription factors capable of controlling the activity of the RNA polymerase II elongation complex. The three-subunit elongin complex was originally purified from rat liver nuclei by its ability to activate the overall rate of elongation by RNA polymerase II, by suppressing transient polymerase pausing at many sites within transcribed sequences. The elongin complex is composed of a transcriptionally active A subunit of...