Fig. 2. PTP-3 is the C. elegans ortholog of the LAR subfamily. (A) Percentage identity and similarity of PTP-3A Immunoglobulin-like (Ig-like) domains, Fibronectin Type III (FNIII) repeats, and phosphatase domains to those of its closest relative (DLAR), and a representative vertebrate LAR family member (rat; RnLAR). The PTP-3B isoform is also shown for comparison; cartoons are not to scale. DLAR contains a ninth FNIII repeat; the FNIII domains of PTP-3 align with the first eight repeats of DLAR. PTP-3A is the largest member of the LAR family; the extra size is mostly due to a larger ‘spacer’ region between the last FNIII repeat and the predicted transmembrane domain. Percentages are calculated from alignments using ClustalW. (B) Alignment of the N-terminal (D1) phosphatase domain of PTP-3 with those of other LAR family members (DLAR, HmLAR2, and rat LAR), using ClustalW. Within the phosphatase domains, DLAR is the most similar protein to PTP-3; within the vertebrate LAR family, PTP proteins are slightly more similar to PTP-3 than are LAR or PTP. The op147 insertion disrupts codon Y1705 in the first phosphatase domain, between the conserved residues YINAN and FWRM. The predicted catalytic cysteine residue C1833 is marked (asterisk). Accession numbers are M27700 (DLAR), AF017083 (HmLAR2), and S46216 (rat LAR). The sequences of PTP-3 cDNAs have been deposited in GenGank, with accession numbers AF316539 (PTP-3A) and AF316540 (PTP-3B).