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.

Abstract

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 pro‐oncoproteins 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.