Elongin C (ELOC)

Elongin C is a protein component of the Elongin (SIII) complex, functioning primarily as a regulatory and adaptor subunit. It forms a heterodimer with Elongin B, which together enhance the activity of the catalytic subunit Elongin A to stimulate RNA polymerase II transcription elongation by suppressing transient pausing[3][4]. Additionally, Elongin C, as part of the Elongin BC complex, serves a key structural role in Cullin RING ubiquitin ligases (specifically the ECS complex with Cullin 2 or Cullin 5), bridging SOCS box-containing substrate adaptors with the Cul–Rbx core to enable substrate ubiquitylation and proteasomal degradation[1][4][5]. This complex is essential in multiple biological processes including cell cycle control, cytokine signal transduction, and tumor suppressor function. Elongin C is targeted by certain viral proteins (e.g., HIV-1 Vif), which hijack the ubiquitin-proteasome pathway for degradation of host antiviral factors[1]. Loss or dysfunction of Elongin C can be linked to impaired proteostasis and cancer, particularly via its role in the VHL tumor suppressor pathway. There is no evidence of direct drugs selectively targeting Elongin C currently in clinical use or development.

Other names

ELOCTranscription elongation factor SIII regulatory subunit CTCEB1

Acts as an adaptor protein connecting Cullin scaffold proteins to SOCS box-containing substrate adaptors, enabling E3 ubiquitin ligase activity and substrate protein ubiquitination and degradation[1][4][5]. Facilitates the suppression of transcription pausing via its role in the Elongin complex with RNA polymerase II[2][3].