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Mutation of hydrophobic residues in the factor Va C1 and C2 domains blocks membrane‐dependent prothrombin activation
Author(s) -
PENG W.,
QUINNALLEN M. A.,
KANE W. H.
Publication year - 2005
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2004.01083.x
Subject(s) - prothrombinase , chemistry , membrane , phosphatidylserine , c2 domain , biophysics , mutant , factor v , amino acid , phospholipid , thrombin , biochemistry , platelet , biology , gene , medicine , surgery , thrombosis , immunology
Summary. The binding of factor (FVa) to phosphatidylserine (PS) membranes regulates assembly of the prothrombinase complex. Two pairs of solvent‐exposed amino acids, Tyr 1956 /Leu 1957 in the C1 domain and Trp 2063 /Trp 2064 in the C2 domain, each make significant contributions to the affinity of FVa for PS membranes, but individually neither pair of amino acids is required for prothrombinase assembly on 25% PS membranes. In this study we characterize a FVa mutant with alanine substitutions in both the C1 and C2 domains: (Y1956,L1957,W2063,W2064)A. We conclude that: (i) prothrombinase assembly on PS membranes requires Trp 2063 /Trp 2064 and/or Tyr 1956 /Leu 1957 ; (ii) combined mutation of Trp 2063 /Trp 2064 and Tyr 1956 /Leu 1957 results in only a modest 4‐fold decrease in the rate of thrombin generation in the absence of membranes; (iii) the present data provide experimental support for the joint participation of the C1 and C2 domains in the binding of FVa to phospholipid membranes as suggested by the recently solved structure for FVai (A1/A3‐C1‐C2).