FIGURE 1.

Primer extension analysis of AMA1, MER2, and MER3 splicing in wild-type or RES deletion strains with or without constitutive expression of MER1. U represents cDNAs from unspliced RNA; S represents cDNA from spliced mRNA. In A, a primer complementary to AMA1 exon 2 was used. In B and C, a CUP1 primer was used, which also primed reverse transcription on endogenous CUP1 RNA. Splicing efficiencies are reported below each lane using the formula S/(S + U) × 100. Primer extension of a polymerase III transcript, 7S RNA, was performed as a loading control.