Elongin B & Elongin C & VHL

Elongin B (ELOB) and Elongin C (ELOC) form a heterodimer that serves as the regulatory subunit for the Elongin complex--a general transcription elongation factor that increases RNA Polymerase II transcription through template-encoded arresting sites. The ELOB/ELOC complex also binds to the "BC-box motif" found in many proteins in the VHL-box and SOCS-box protein families. In this function, ELOB/ELOC serves as an adapter between substrate recognition proteins and either Cullin-2/Rbx1 (in VHL-box E3 Ubiquitin ligases) or Cullin-5/Rbx2 (in SOCS-box E3 Ubiquitin ligases). VHL is involved in the ubiquitination and subsequent proteasomal degradation via the von Hippel-Lindau ubiquitination complex. It seems to act as a target recruitment subunit in the E3 ubiquitin ligase complex and recruits hydroxylated hypoxia-inducible factor (HIF) under normoxic conditions. Involved in transcriptional repression through interaction with HIF1A, HIF1AN and histone deacetylases.