Isolation and sequence of the canine pancreatic phospholipase A2 gene

A genomic library has been constructed in EMBL3 lambda phage using high molecular mass DNA isolated from canine spleen. A cDNA clone, shown to code for preprophospholipase A2 which is processed to the prosecretory form prior to release from secretory cells, was used to identify a lambda clone which contains the complete phospholipase A2 gene. Restriction enzyme and DNA sequence analysis indicate that the primary transcriptional unit for the phospholipase gene, approximately 9.0 kb, is organized into four exon sequences. Exon 1 encodes the 5' nontranslated sequence, the ATG initiation codon, and the hydrophobic core of the signal peptide. Exons 2-4 encode regions of the peptide of residues -11 to 43, 43 to 86 and 86 to 124, respectively. The 5' flanking region shows a TATA box at position -29 and multiple CAAT boxes at positions -279, -206, -183 and -159. Regions of the 5' flanking sequence in the canine sequence, from nucleotides -47 to -74 and -91 to -129, show high similarity to similar regions in the human gene. However, an analysis of 400 nucleotides of the 5' flanking sequence in transient expression studies was unable to identify tissue-specific promoter or enhancer sequences. Within 5' nontranslated regions the canine and human genes share a pyrimidine-rich sequence which may be involved in differential regulation of mRNA translation.