Defective propeptide processing of blood clotting factor IX caused by mutation of arginine to glutamine at position -4

Cell. 1986 May 9;45(3):343-8. doi: 10.1016/0092-8674(86)90319-3.


Blood clotting factor IX is synthesized as a precursor polypeptide that would be expected to be proteolytically cleaved in at least two positions during maturation to remove the prepeptide and propeptide regions. We show that a point mutation causing hemophilia B changes the amino acid at position -4 in the propeptide region of factor IX from an arginine to a glutamine, which results in the expression of a stable longer protein with 18 additional amino acids of the N-terminal propeptide region still attached. This suggests that in the normal maturation of factor IX the signal peptidase cleaves the peptide bond between amino acid residues -18 and -19, generating an unstable profactor IX intermediate. Further proteolytic processing to the mature factor IX depends on the arginine residue at -4. The significance of the homologous arginine residue in other processed proteins is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cloning, Molecular
  • Cross Reactions
  • DNA Restriction Enzymes
  • Factor IX / genetics*
  • Factor IX / immunology
  • Factor IX / metabolism
  • Hemophilia B / genetics*
  • Humans
  • Peptide Hydrolases / metabolism
  • Protein Processing, Post-Translational
  • Protein Sorting Signals / metabolism*
  • Substrate Specificity


  • Protein Sorting Signals
  • Factor IX
  • DNA Restriction Enzymes
  • Peptide Hydrolases

Associated data

  • GENBANK/M13154