A testis-specific transcription factor IIA (TFIIA tau) stimulates TATA-binding protein-DNA binding and transcription activation

The general transcription factor IIA (TFIIA) stimulates RNA polymerase II-s pecific transcription by stabilizing the association of the TATA-binding pr otein (TBP) with promoter DNA, inhibiting repressors of TBP, and facilitati ng activator-dependent conformational changes in the preinitiation complex. TFIIA is encoded by two genes (alpha beta and gamma) that are highly conse rved between human and yeast. Here, we report the molecular cloning of a no vel human gene that shares significant sequence similarity to the evolution arily conserved amino- and carboxyl-terminal domains of TFIIA alpha beta. T he TFIIA-related protein (TFIIA tau) was cloned from a testis-specific cDNA library, and its mRNA is expressed predominantly in testis tissue as deter mined by expressed sequence tag data base analysis and Northern blotting an alysis. The TFIIA complex reconstituted with the testis-specific subunit, T FIIA (tau+gamma), formed the TFIIA-TBP-TATA DNA (T-A) and TFIIA-TFIIB-TBP-T ATA DNA (TAB) complexes indistinguishably hom TFIIA (alpha beta+gamma), TFI IA (tau+gamma) supported basal and activated transcription for most activat ors in reactions reconstituted with TFIIA-depleted nuclear extracts. Howeve r, TFIIA (tau+gamma) was reduced relative to TFIIA (alpha beta+gamma) for s timulating transcription with at least one activator, suggesting that these two forms of TFIIA have activator specificity. These results suggest that TFIIA tau may be important for testis specific transcription regulation.