Rapid communication: Nucleotide sequences of two isoforms of porcine micromolar calcium-activated neutral protease 1 cDNA.

Name of Sequences. Porcine micromolar calcium-activated neutral protease 1 isoforms A and B (CAPN1A, CAPN1B) cDNA. Genus and Species. Sus scrofa (Meishan ×White Composite). Origin of Clones. Primers (mu1725 and mu1840; Smith et al., 2000) developed from the complete cDNA sequence of bovine CAPN1 (GenBank accession no. AF221129) were used to screen one embryonic and one adult pooled tissue porcine cDNA library (Fahrenkrug et al., unpublished data) by an iterative process as described (Smith et al., 1995). One full-length cDNA clone was obtained from each library. The pCAPN1A isoform was obtained from the adult tissue library, and isoform pCAPN1B was obtained from the embryonic cDNA library. Comparison with Related Species. The 2,142-bp open reading frame of pCAPN1A cDNA sequence has 94% and 92% identity with the bovine (GenBank accession no. AF221129) and human (GenBank accession no. X04366) sequences, respectively. Conceptual translation predicts a protein of 714 amino acids with 96% and 95% identity to bovine and human proteins, respectively. The pCAPN1B cDNA sequence has a 1,941-bp open reading frame that is 100% identical to the first 1,941 bases of the pCAPN1A cDNA. Sequence Data. The truncated reading frame of pCAPN1B results from a 496-bp insertion into the sequence of pCAPN1A, which introduces a stop codon immediately after the site of insertion. Following the inserted sequence, the sequence of pCAPN1B is identical to the remainder of pCAPN1A throughout the coding region and the 3′untranslated region (3′UTR). The position of the insertion is identical to the boundary between exon 17 and exon 18 of the bovine CAPN1 gene (Smith et al., 2000). Therefore we tested the possibility that the insertion resulted from a retained intron, using primers (mu1896 and mu2239; Smith et al., 2000) that flank intron 17 and 18 of the bovine gene. These primers were used to amplify the corresponding region from a Bacterial Artificial Chromosome clone containing the