FIG. 6.

A mutant G element will bind in extract to a U1 snRNP containing a complementary mutated U1 snRNA. (A) Sequences of the 5′ ends of wild-type (Wt) U1 RNA and U1 RNAs modified to complement wild-type or mutant G1 elements. (B) Wild-type and mutant G1-G2 RNAs were incubated in nuclear extracts prepared from cells transfected with the U1 snRNA genes shown in panel A and analyzed by immunoprecipitation (IP) with an anti-U1 70K antibody. Precipitated RNAs were separated on a 5% polyacrylamide–8.3 M urea denaturing gel and visualized by autoradiography.