Blood clotting factor IX Nagoya 3: the molecular defect of zymogen activation caused by an arginine-145 to histidine substitution

Thromb Res. 1990 Nov 15;60(4):311-20. doi: 10.1016/0049-3848(90)90109-p.


Factor IX Nagoya 3 (IX Nagoya 3) is a natural mutant of factor IX recognized in a patient with moderately severe hemophilia B. The patient had 0.60 units/ml of factor IX antigen and 2-5% of clotting activity. IX Nagoya 3 was purified from the patient's plasma by immunoaffinity chromatography with an anti-factor IX monoclonal antibody column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the treatment of IX Nagoya 3 with factor XIa/calcium ions resulted in cleavage only at the Arg180-Val181 bond. The amino acid sequence analysis of one of the lysyl endopeptidase peptides derived from IX Nagoya 3 revealed that Arg-145 is replaced by His. This substitution impairs the cleavage between the light chain and the activation peptide by factor XIa/calcium ions.

MeSH terms

  • Amino Acid Sequence
  • Calcium / metabolism
  • Factor IX / chemistry
  • Factor IX / genetics*
  • Factor IX / metabolism
  • Factor XIa / metabolism
  • Humans
  • In Vitro Techniques
  • Molecular Sequence Data
  • Mutation


  • factor IX Nagoya 3
  • Factor IX
  • Factor XIa
  • Calcium