Figure 5.

U1antiGFPtpz fails to inhibit GFPsaph expression but U1antiGFPsaph reduces GFPsaph expression. NIH 3T3 cells were co-transfected with pOB₄GFPsaph alone or pOB₄GFPsaph plus U1 snRNA, U1antiGFPtpz or U1antiGFPsaph and selected with 100 µg/ml hygromycin for 4 weeks. (A) Fluorescence microscopy of pOB₄GFPsaph cells transfected with U1antiGFPtpz: (1) parental pOB₄GFPsaph cells; (2) pOB₄GFPsaph cells transfected with U1 snRNA; (3) pOB₄GFPsaph cells transfected with U1antiGFPtpz433 which has a 1 bp mismatch compared with GFPsaph; (4) pOB₄GFPsaph cells transfected with U1antiGFPtpz1196 which has a 2 bp mismatch compared with GFPsaph. (B) Northern blot of RNA from pooled clonal cells shown in (A) hybridized with GFP and 18S probes. (C) Fluorescence microscopy (×100) of pOB₄GFPsaph versus U1antiGFPsaph. The four panels are arranged as described in (A) except that there is no mismatch between GFPsaph and U1antiGFPsaph433 or U1antiGFPsaph196. (D) Northern blot of RNA from pooled clonal cells shown in (C). See (B) for labeling details.