Thromb Haemost 2000; 84(03): 413-419
DOI: 10.1055/s-0037-1614037
Commentary
Schattauer GmbH

Protein S Thr103Asn Mutation Associated with Type II Deficiency Reproduced In Vitro and Functionally Characterised

Authors

  • Tusar Kanti Giri

    1   From the Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital Malmö, Malmö, Sweden
  • Pablo García de Frutos

    1   From the Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital Malmö, Malmö, Sweden
  • Björn Dahlbäck

    1   From the Department of Laboratory Medicine, Division of Clinical Chemistry, Lund University, University Hospital Malmö, Malmö, Sweden

This work was supported by the Swedish Medical Research Council (grants 07143, 12561 and 13000), a Senior Investigators Award from the Swedish Foundation for Strategic Research, research funds from the University Hospital in Malmö, the Fondation Louis-Jeantet de Médecine, the Alfred Österlund Trust, and the Albert Påhlsson Trust.
Weitere Informationen

Publikationsverlauf

Received 14. Februar 2000

Accepted after resubmission 10. April 2000

Publikationsdatum:
14. Dezember 2017 (online)

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Summary

Protein S functions as a cofactor to activated protein C (APC) in the degradation of FVa and FVIIIa. In protein S, the thrombin sensitive region (TSR) and the first EGF-like domain are important for expression of the APC cofactor activity. A naturally occurring Thr103Asn (T103N) mutation in the first EGF-like domain of protein S has been associated with functional (type II) protein S deficiency. To elucidate the functional consequences of the T103N mutation, recombinant protein S mutant was expressed in mammalian cells and functionally characterised. The expression level of protein S T103N from transiently transfected COS 1 cells was equal to that of wild type protein S. The mutant protein S and wild type protein S were also expressed in 293 cells after stable transfection, and the recombinant proteins purified. In APTT-and PT-based coagulation assays, the mutant protein demonstrated approximately 50% lower anticoagulant activity as compared to wild type protein S. The functional defect was further investigated in FVa-and FVIIIa-degradation assays. The functional defect of mutant protein S was attenuated at increasing concentrations of APC. The results demonstrate the region around residue 103 of protein S to be of functional importance, possibly through a direct interaction with APC.