MOLECULAR-CLONING AND ANALYSIS OF 2 SUBUNITS OF THE HUMAN TFIID COMPLEX - HTAF(II)130 AND HTAF(II)100

Transcription factor TFIID is a multiprotein complex composed of the T ATA box-binding protein (TBP) and multiple TBP-associated factors (TAF s), TFIID plays an essential role in mediating transcriptional activat ion by gene-specific activators, Numerous transcriptional activators h ave been characterized from mammalian cells; however, molecular analys is of the components of mammalian TFIID has been incomplete, Here we d escribe isolation of cDNAs encoding two TAF subunits of the human tran scription factor TFIID, The first cDNA is predicted to encode the C-te rminal 947 residues of the 130-kDa human TAF subunit, hTAF(II)130, The second cDNA encodes the C-terminal 801 residues of the 100-kDa subuni t, hTAF(II)100. Recombinant TAFs expressed in human cells by transient transfections are capable of associating with the endogenous TAFs and TBP to form a TFIID complex in vivo. Protein binding experiments demo nstrate that hTAF(II)130, like its Drosophila homolog dTAF(II)110, int eracts with the glutamine-rich activation domains of the human transcr iption factor Spl. Furthermore, hTAF(II)130 shows reduced binding to t he Spl mutants with impaired ability to activate transcription, sugges ting a role for hTAF(II)130 as a direct coactivator target for Sp1.