Copper resistances of reporter yeast with mutant act1-CUP1 plasmids with two 3′ splice sites. (A) Sequences of ACT1-CUP1 plasmids showing the region near the 3′ splice site, emphasizing the branch point and 3′ splice sites. Wild-type ACT1-CUP1 (WT), the shortened Sh substrate, and the alternative splicing substrates AS1 and AS2 are shown. Exon bases shown as NNN were mutated. Base differences between the new plasmids and ACT1 are underlined. (B) Copper resistances conferred on prp18ΔCR (Left) and PRP18-wt (Right) yeast by plasmids based on WT ACT1-CUP1 (1–4), Sh (5–8), AS1 (9–25), or AS2 (26–29). The 3′ splice site(s) is (are) shown at the Left. In plasmids 22 and 23, the last four bases of exon1 were changed from TCTG to AAAA. The figure is a composite of plates from a single experiment with prp18ΔCR yeast and a single experiment with PRP18 yeast. The original colors were individually adjusted for conversion to black and white.