cDNA cloning of a novel P-I lebetase isoform Le-4

In order to better understand the function of fibrinolytic enzyme lebetase isoforms and the synthesis of disintegrins we have isolated a cDNA encoding the most basic isoform (Le-4) from the cDNA library prepared from the poly(A)+ RNA of the venomous gland of an individual Vipera lebetina snake. The truncated 5′-sequence of 1112 basepairs encodes the mature protein with 203 amino acid residues with calculated isoelectric point and size of 5.6 and 22,930 Da, respectively. Multiple comparison of the deduced amino acid sequence of the metalloprotease part of Le-4 is related to short reprolysins, identities were within the range of 60-87%. The two lebetase isoforms are synthesized in different way: Le-4 is synthesized with metalloprotease domain only; Le-3 is synthesized with metalloprotease and disintegrin-like domain and processed posttranslationally. The sequence of the disintegrin-like part of Le-3 is identical to A-chain of the heterodimeric disintegrin VLO5 from Vipera lebetina obtusa venom (Calvete et al., 2003).