Figure 4.

 Two alternatively spliced clr-1 transcripts. (A) Genomic organization of the 9-kb (StuI–StuI) clr-1 genomic rescuing fragment. (Solid boxes) Coding sequence; (hatched boxes) untranslated regions of cDNA1. The SL1 trans-spliced leader sequence is found at the 5′ end of clr-1 transcripts. Domains identified on the basis of sequence similarity are labeled: (C-rich) Cysteine-rich; (IG) immunoglobulin-like; (FN) fibronectin type III repeat; (TM) transmembrane; (D1,D2) phosphatase domains 1 and 2. The deletion associated with clr-1(e2530) is indicated above the clr-1 genomic structure. (^) Alternate splice-donor sites. (B) The two transcripts corresponding to clr-1 differ in the use of a single splice–donor site. Genomic sequence surrounding the alternative splice is shown on the first line. Exons are boxed; the intron is in parenthesis. (Dashed box) Additional seven nucleotides found in cDNA1, which maintains an ORF that extends beyond the phosphatase domains. The splice that generates cDNA2 creates a UGA stop codon (*) just downstream of the splice–acceptor site. (C) clr-1-rescuing activity of the individual alternatively spliced clr-1 forms. Diagrams of the predicted protein products of the constructs introduced by germ-line transformation are shown. (Horizontal line) Cell membrane; (half circles) immunoglobulin domains; (hatched boxes) FN III repeats; (solid boxes) phosphatase domains. DNA constructs were tested for rescue in both F₁ transformants (Rescued F1s) and stable lines (Rescued lines).