Fig. 3.
Protein–protein interaction studies. (A) Coimmunoprecipitation experiments using EBV-positive BJAB-B1 cell lysate and antibodies to SFPQ, NONO, RBM14, and PAX5 described in refs. 6, 18. Isotype control (IgG) and anti-AUF1 antibodies were included as negative controls. RNase A treatment was carried out before immunoprecipitation (Materials and Methods). PAX5 interaction with SFPQ, NONO, and RBM14 is observed, suggesting the presence of a complex containing all four proteins. (B) Selection by MBP–Pax5 (Pulldown) of recombinant proteins shown in Fig. 2C. Western blot analyses using anti-FLAG and anti-His antibodies to detect FLAG–SFPQ, FLAG–NONO, His–RBM14, or His–AUF1p40 were carried out to examine binding to PAX5. SFPQ and NONO bind PAX5, whereas RBM14 and AUF1 exhibit no interaction. Input samples (Left) and proteins bound to MBP–Pax5 (Right) are shown.