Fig 1. Association of splicing factors with a human RNA Pol II-containing complex.
SR proteins, the U2AF65 factor, the Y12-68K polypeptide and Sm proteins co-purify with a RNA Pol II-containing complex on a GST-SII affinity column. Western blot analysis of purified SR proteins (lane 1), HeLa nuclear extract (NE) (lane 2), HeLa whole cell extract (WCE) (lane 3), the GST-SII column eluate (lane 4), and the GST column eluate (lane 5) was performed using antibodies directed against the N terminus of the RPB1 subunit of RNA Pol II (Ab N-20) and detecting both the hypophosphorylated (IIA) and hyperphosphorylated (IIO) forms. Antibodies directed against different general transcription factors were also used (only experiments using anti-TBP and anti-RAP30 are shown). In addition, the monoclonal Ab104 and Y12 antibodies revealed the presence of SR, Sm, and Y12–68K proteins.