CIF150, a human cofactor for transcription factor IID-dependent initiator function.
The transcription factor IID (TFIID) complex is highly conserved between the Drosophila and mammalian systems. A mammalian homolog has been described for all the Drosophila TATA box-binding protein-associated factors (TAFs), with the exception of dTAF(II)150. We previously reported the identification of CIF, an essential cofactor for TFIID-dependent transcription from promoters containing initiator (Inr) elements. Here we describe the molecular cloning of CIF150, the human homolog of dTAF(II)150, and present biochemical evidence that this factor is involved in Inr activity. CIF150 is capable of mediating TFIID-dependent Inr activity in a complementation assay, and a protein fraction lacking Inr activity lacks detectable amounts of CIF150. Despite the striking similarity to dTAF(II)150, CIF150 does not appear to be associated with human TFIID. However, in vitro binding assays revealed a specific and direct interaction between CIF150 and hTAF(II)135. This interaction might be structurally important for the functional interaction between CIF150 and human TFIID, since CIF150 stabilizes TFIID binding to a core promoter.
Kaufmann
J
J
Institute for Molecular Biology and Tumor Research, Philipps University, Marburg, Germany. Joerg_Kaufmann@chiron.com
Ahrens
K
K
Koop
R
R
Smale
S T
ST
Müller
R
R
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D016385:TATA Box; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000235:genetics*; D019473:Transcription Factors, TFII / Q000235:genetics*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; C486221:TAF2 protein, human; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D019473:Transcription Factors, TFII