This family represents a conserved region within RNA polymerase II transcription factor SIII (Elongin) subunit A. In mammals, the Elongin complex activates elongation by RNA polymerase II by suppressing transient pausing of the polymerase at many sites within transcription units. Elongin is a heterotrimer composed of A, B, and C subunits of 110, 18, and 15 kilodaltons, respectively. Subunit A has been shown to function as the transcriptionally active component of Elongin [1].

1: Elongin (SIII): a multisubunit regulator of elongation by RNA polymerase II. Aso T, Lane WS, Conaway JW, Conaway RC; Science 1995;269:1439-1443. PMID:7660129