Themarine snailConusis the sole invertebratewherein both the vitamin K-dependent carboxylase and its product, c-carboxyglutamic acid, have been identified. To examine its biosynthesis of c-carboxyglutamic acid, we studied the carboxylase from Conusvenom ducts. The carboxylase cDNA fromConus textilehas an ORF that encodes a 811-amino-acid proteinwhich exhibits sequence similarity to the vertebrate carboxylases, with 41% identity and 60% sequence similarity to the bovine carboxylase.
