Structural Characteristics and Evolution of the Protobothrops elegans Pancreatic Phospholipase A2 Gene in Contrast with Those of Protobothrops Genus Venom Phospholipase A2 Genes

The nucleotide sequence of the gene encoding Protobothrops elegans (Crotalinae) pancreatic phospholipase A(2) (PLA(2)), abbreviated PePancPLA(2), was determined by means of inverted PCR techniques. Since its deduced amino acid sequence contains a pancreatic loop and shows high similarity to that of Laticauda semifasciata (Elapinae) group IB pancreatic PLA(2), PePancPLA(2) is classified into group IB PLA(2). The nucleotide sequences of the PePancPLA(2) gene, the L. semifasciata group TB pancreatic PLA(2) gene, and the L. semifasciata group IA venom PLA(2) gene are similar to one another but greatly dissimilar to those of Protobothrops genus (Crotalinae) group II venom PLA(2) genes, suggesting that the Elapinae group IB PLA(2) gene and the group IA PLA(2) gene appeared after Elapinae was established, and that the Crotalinae group II venom PLA(2) genes came into existence before Elapinae and Crotalinae diverged. A phylogenetic analysis of their amino acid sequences confirms this.