cDNA cloning of the two subunits of phospholipase A(2) inhibitor PLI gammafrom blood plasma of the Chinese mamushi, Agkistrodon blomhoffii siniticus

Three phospholipase A(2) (PLA(2)) inhibitors (PLI) have been purified from the blood plasma of the Chinese mamushi, Agkistrodon blomhoffii siniticus; 1 of these, PLI gamma, contains 2 homologous subunits, PLI gamma-A and PLI gamma-B. The cDNAs encoding these 2 subunits of PLI gamma were isolated fro m a liver cDNA library by using fragments from polymerase chain reaction am plifications as probes and sequenced. The respective nucleotide sequences e ncoded 19-residue signal sequences, followed by 181-residue proteins. The c alculated molecular masses were 20123 and 20150 Da for the PLI gamma-A and PLI gamma-B subunits, respectively; and PLI gamma-A included a N-linked car bohydrate site at Asn-157, The sequences of these subunits contained 2 inte rnal repeats of disulfide-bonding pattern characteristic to those of urokin ase-type plasminogen activator receptor and members of the Ly-6 superfamily . A phylogenetic analysis comparing the amino acid sequences of PLI gamma-A and PLI gamma-B with those for other snakes revealed that the gene duplica tion leading to these 2 subunits occurred before the divergence of Viperida e and Elapidae.