Identification of a general transcription factor TFIIA alpha/beta homolog selectively expressed in testis

In this paper we describe the isolation of a cDNA that encodes a human TFII A alpha/beta-like factor (ALF). The open reading frame of ALF predicts a pr otein of 478 amino acids that contains characteristic N- and C-terminal con served domains separated by an internal nonconserved domain, In addition, a rare ALF-containing cDNA, which possesses an extended N terminus (Stoned B /TFIIA alpha/beta-like factor; SALF) has also been identified. The results of Northern and dot blot analyses show that ALF is expressed almost exclusi vely in testis; in contrast, TFIIA alpha/beta and TFIIA gamma are enriched in testis but are also widely expressed in other human tissues; Recombinant ALF (69 kDa) and TFIITA gamma (12 kDa) polypeptides produced in Escherichi a coli form an ALF/gamma complex that can stabilize TBP-TATA interactions i n an electrophoretic mobility shift assay. The ALF/gamma complex is also ab le to restore transcription from the adenovirus major late promoter using H eLa cell nuclear extracts that have been depleted of TFIIA, Overall, the da ta show that ALF is a functional homolog of human general transcription fac tor TFIIA alpha/beta that may be uniquely important to testis biology.