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Site‐directed mutagenesis but not γ‐carboxylation of Glu‐35 in factor VIIa affects the association with tissue factor
Author(s) -
Persson Egon,
Nielsen Lars S.
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00400-0
Subject(s) - tissue factor , chemistry , carboxylation , factor x , mutagenesis , asparagine , biochemistry , site directed mutagenesis , mutant , cofactor , factor ix , thrombin , amino acid , enzyme , biology , coagulation , gene , psychology , platelet , psychiatry , immunology , catalysis
Factor VIIa is a vitamin K‐dependent enzyme whose γ‐carboxyglutamic acid (Gla)‐containing domain is important for calcium ion‐dependent binding to the cofactor tissue factor and membrane surfaces. This domain contains 10 Gla residues, the individual roles and importance of which are not known. Comparisons with the homologous protein C, factor IX and prothrombin may provide functional information on the first nine Gla residues, whereas no data can be extrapolated to Gla‐35 in factor VIIa. Therefore, the effects of posttranslational γ‐carboxylation and site‐directed mutagenesis of Glu‐35 were investigated. Mutations to Asp, Gln or Val all lead to a lower affinity for tissue factor by decreasing the rate of association, in the case of the Val mutant by a factor of 200, as measured by surface plasmon resonance. In contrast, Glu or Gla side chains at position 35 appear to fulfil the functional roles equally well.