Factor X-activating glycoprotein of Russell's viper venom: Polypeptide composition and characterization of the carbohydrate moieties

D. Channe Gowda, Craig M. Jackson, Preston Hensley, Eugene A. Davidson

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There is contradictory information regarding the molecular weight and polypeptide chain composition of RVV-X, a glycoprotein in Russell's viper venom that is capable of activating factor X to Xa. We show that RVV-X is a 92,880-Da glycoprotein. It consists of three disulfide-linked polypeptide chains, one heavy chain (α-chain, Mr 57,600) and two light chains (β- and γ-chains, Mr 19,400 and 16,400, respectively). The two light chains seen on SDS-polyacrylamide gel electrophoresis under reducing conditions are two distinct components of the molecule, rather than a heterogeneous mixture of a single chain as previously reported (Takeya, H., Nishida, S., Miyata, T., Kawada, S., Saisaka, Y., Morita, T., and Iwanaga, S. (1992) J. Biol. Chem. 267, 14109-14117). The following evidence supports this conclusion, (i) The two light chains of RVV-X are present in equal proportion. (ii) The estimated molecular weight of an α1β1γ1-structure closely matches the molecular weight determined by matrix-assisted laser desorption mass spectrometry. (iii) The amino acid compositions and NH2-terminal sequences of the β- and γ-chains are different. (iv) Although both the β- and γ-chains contain one N-linked oligosaccharide chain each, they are glycosylated differentially. RVV-X contains six N-linked oligosaccharides, four in the α-chain and one in each of the β- and γ-chains. The carbohydrate structures are different from those known for other snake venom glycoproteins, and they resemble closely those in various mammalian glycoproteins. The majority of the oligosaccharides are complex bi-, tri-, and tetraantennary structures, with a small proportion of multiantennary and high mannose-type structures. Two notable structural features of RVV-X oligosaccharides are as follows. (i) Sialic acid residues are linked to β-galactosyl residues solely by α2,3-linkages, and (ii) bi-secting N-acetylglucosamine residues are present in the majority of the oligosaccharides.

Original languageEnglish (US)
Pages (from-to)10644-10650
Number of pages7
JournalJournal of Biological Chemistry
Issue number14
StatePublished - Apr 8 1994

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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