Transcription Elongation Factor B Polypeptide 3C Like Protein 1 (TCEB3CL)

The SIII (or elongin) transcription elongation factor complex stimulates the rate of transcription elongation by RNA polymerase II by suppressing the transient pausing of the polymerase at many sites along the DNA template. This complex is a heterotrimer, composed of the transcriptionally active subunit A, A2 or A3 (or elongin A, A2 or A3) and two regulatory subunits, B and C (or elongin B and C).

TCEB3CL encodes subunit A3. A3 and A are ubiquitously expressed, whereas A2 is specifically expressed in the testis. SIII, also known as elongin, is a general transcription elongation factor that increases the RNA polymerase II transcription elongation past template-encoded arresting sites. Subunit A3 is transcriptionally active but its transcription activity is not enhanced by binding to the dimeric complex of the SIII regulatory subunits B and C.