Elongin A2 (ELOA2)

TCEB3B encodes the transcriptionally active subunit of the SIII (or elongin) transcription elongation factor complex, which also includes two regulatory subunits, elongins B and C. This complex acts to increase the rate of RNA chain elongation by RNA polymerase II by suppressing transient pausing of the polymerase at many sites along the DNA template. Whereas a related protein with similar function, elongin A, is ubiquitously expressed, the encoded protein is specifically expressed in the testis, suggesting it may have a role in spermatogenesis. The deduced 753-amino acid protein has a calculated molecular mass of 83.9 kD. Elongin A2 shares 47% amino acid identity with elongin A, and both proteins contain an N-terminal SII similarity domain and a C-terminal elongin B/C-binding motif. Northern blot analysis of several human tissues detected a 3.0-kb transcript only in testis.