Defective propeptide processing of blood clotting factor IX caused by mutation of arginine to glutamine at position -4.
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Bentley AK, Rees DJ, Rizza C, Brownlee GG
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.
- PubMed ID
- 3009023 [ View in PubMed]
- Abstract
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.