Wild-type U 1 RNA and 1 28 pre-mRNA 22.4 The spliceosome Normal splicing contains SnRNas 6 exon INtron 3 adenovirus splice site igure 22.9 wild-type U1 sn RNA and mutant 125 pre-mRNA Mutations that No splicing abolish function of thes￠ splicing site exon GU G AA U intron 31 can be suppressed by mutant splice site compensating Mutant 1 snRNA and mutant 1 2S RNA Splicing restored mutations in U1 snrna that restore ba ase pairin g U^5 6 exon GU GAAUintron 3 消当Figure 22.9 Mutations that abolish function of the 5￠ splicing site can be suppressed by compensating mutations in U1 snRNA that restore base pairing. 22.4 The spliceosome contains snRNAs