The propeptide region of clotting factor IX is a signal for a vitamin K dependent carboxylase: evidence from protein engineering of amino acid -4.

AUTOR(ES)

Galeffi, P

RESUMO

Homologous "propeptide" regions are present in a family of vitamin K-dependent mammalian proteins, including clotting factors II, VII, IX, X, protein C, protein S and bone "gla" proteins. To test the hypothesis that the propeptide is a signal for the correct gamma-carboxylation of the adjacent gamma-carboxy region, we have mutated amino acid -4 of human factor IX from an arginine to a glutamine residue, by M13-directed site-specific mutagenesis of a cDNA clone. After expression of mutant factor IX in dog kidney cells, we find that it is secreted into the medium in a precursor form containing the propeptide, and is inefficiently gamma-carboxylated compared to the control, wild-type, recombinant factor IX. This result supports the hypothesis that the propeptide region is required for efficient gamma-carboxylation of factor IX in dog kidney cells. Furthermore, it confirms previous results that arginine at amino acid -4 is required for correct propeptide processing.

Documentos Relacionados

• Vitamin K-dependent carboxylase: evidence for a hydroperoxide intermediate in the reaction.
• Vitamin K-dependent carboxylase: possible role of the substrate "propeptide" as an intracellular recognition site.
• Vitamin K-dependent carboxylase: affinity purification from bovine liver by using a synthetic propeptide containing the gamma-carboxylation recognition site.
• Mechanism of cyanide inhibition of the blood-clotting, vitamin K-dependent carboxylase.
• Isolation and characterization of vitamin K-dependent region of bovine blood clotting factor X.