hTAF(II)68, a novel RNA/ssDNA-binding protein with homology to the pro-oncoproteins TLS/FUS and EWS is associated with both TFIID and RNA polymerase II

TFIID is the main sequence-specific DNA-binding component of the RNA polymerase II (Pol II) transcriptional machinery, It is a multiprotein complex composed of the TATA-binding protein (TBP) and TBP-associated factors (TAF(II)s). Here we report the cloning and characterization of a novel human TBP-associated factor, hTAF(II)68. It contains a consensus RNA-binding domain (RNP-CS) and binds not only RNA, but also single stranded (ss) DNA, hTAF(II)68 shares extensive sequence similarity with TLS/FUS and EWS, two human nuclear RNA-binding prooncoproteins which are products of genes commonly translocated in human sarcomas, Like hTAF(II)68, TLS/FUS is also associated with a sub-population of TFIID complexes chromatographically separable from those containing hTAF(II)68. Therefore, these RNA and/or ssDNA-binding proteins may play specific roles during transcription initiation at distinct promoters, Moreover, we demonstrate that hTAF(II)68 co-purifies also with the human RNA polymerase II and can enter the preinitiation complex together with Pol II.