Thromb Haemost 1995; 74(04): 1003-1008
DOI: 10.1055/s-0038-1649869
Original Article
Clinical Studies
Schattauer GmbH Stuttgart

Protein C Osaka 10 with Aberrant Propeptide Processing: Loss of Anticoagulant Activity Due to an Amino Acid Substitution in the Protein C Precursor

Toshiyuki Miyata
1   The Research Institute, National Cardiovascular Center, Fujishirodai, Japan
,
Yan-Zhen Zheng
1   The Research Institute, National Cardiovascular Center, Fujishirodai, Japan
,
Toshiyuki Sakata
2   The Department of Clinical Laboratory, National Cardiovascular Center, Fujishirodai, Japan
,
Hisao Kato
1   The Research Institute, National Cardiovascular Center, Fujishirodai, Japan
› Institutsangaben
Weitere Informationen

Publikationsverlauf

Received 21. Februar 1995

Accepted after resubmission 21. Juni 1995

Publikationsdatum:
27. Juli 2018 (online)

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Summary

We studied the molecular basis of protein C deficiency in a family with a history of thromboembolic disease. An approximately 50% reduction in anticoagulant activity despite normal levels of protein C amidolytic activity and antigen was detected in plasma from the proband. All the exons and intron/exon junctions of the protein C gene were studied using a strategy that combined polymerase chain reaction amplification with DNA sequencing of the amplified fragments. We identified a C-to-A change at nucleotide number 1387 of the protein C gene in the proband and his mother, and this mutant was designated protein C Osaka 10. The C-to-A change resulted in the substitution of Ser for Arg at position -1, which is the processing protease cleavage site. The mutant protein C was partially purified from plasma of the patient’s mother using barium adsorption followed by ion-exchange column chromatography. It eluted at the same sodium chloride concentration as normal protein C, and thus γ-carboxylation of the mutant protein appeared to be normal. The apparent molecular weight of this mutant protein C was the same as that of the normal protein on immunoblotting. Amino-terminal sequence analysis showed that the light chain of the mutant protein C had an additional Ser at position -1. Thus, the loss of anticoagulant activity of protein C Osaka 10 can be explained by alteration of the conformation of the Gla domain by the additional Ser in the mutant molecule.