Molecular cloning and characterization of ecto-5′-nucleotidase from the venoms of Gloydius blomhoffi

A Gloydius blomhoffi brevicaudus venom gland cDNA library was screened to isolate cDNA clones using probes based on highly conserved amino acid sequences from known ecto-5′-nucleotidases (ecto-5′-NTs). Molecular cloning of ecto-5′-NT from G. blomhoffi brevicaudus venom predicted that it was a glycosyl phosphatidylinositol-anchored membrane protein containing 588 amino acid residues with 7 potential N-linked glycosylation sites. The deduced amino acid sequence shows approximately 60% sequence identity to mammalian ecto-5′-NT sequences. This is the first report of the primary structure of ecto-5′-NT from a reptile. Gel-filtration chromatography of fresh venom from Gloydius blomhoffi blomhoffi, a subspecies of G. blomhoffi, revealed that at least a part of ecto-5′-NT is bound to exosome-like vesicles.