Identification of Functionally Important Amino Acid Residues within the C2-Domain of Human Factor V Using Alanine-Scanning Mutagenesis
We have previously determined that the C2-domain of human factor V (residues 2037−2196) is required for expression of cofactor activity and binding to phosphatidylserine (PS)-containing membranes. Naturally occurring factor V inhibitors and a monoclonal antibody (HV-1) recognized epitopes in the ami...
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Published in | Biochemistry (Easton) Vol. 39; no. 8; pp. 1951 - 1958 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
29.02.2000
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Subjects | |
Online Access | Get full text |
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Summary: | We have previously determined that the C2-domain of human factor V (residues 2037−2196) is required for expression of cofactor activity and binding to phosphatidylserine (PS)-containing membranes. Naturally occurring factor V inhibitors and a monoclonal antibody (HV-1) recognized epitopes in the amino terminus of the C2-domain (residues 2037−2087) and blocked PS binding. We have now investigated the function of individual amino acids within the C2-domain using charge to alanine mutagenesis. Charged residues located within the C2-domain were changed to alanine in clusters of 1−3 mutations per construct. In addition, mutants W2063A, W2064A, (W2063, W2064)A, and L2116A were constructed as well. The resultant 30 mutants were expressed in COS cells using a B-domain deleted factor V construct (rHFV des B). All mutants were expressed efficiently based on the polyclonal antibody ELISA. The charged residues, Arg2074, Asp2098, Arg2171, Arg2174, and Glu2189 are required for maintaining the structural integrity of the C2-domain of factor V. Four of these residues (Arg2074, Asp2098, Arg2171, and Arg2174) correspond to positions in the factor VIII C-type domains that have been identified as point mutations in patients with hemophilia A. The epitope for the inhibitory monoclonal antibody HV-1 has been localized to Lys2060 through Glu2069 in the factor V C2-domain. The epitope for the inhibitory monoclonal antibody 6A5 is composed of amino acids His2128 through Lys2137. The PS-binding site in the factor V C2-domain includes amino acid residues Trp2063 and Trp2064. This site overlaps with the epitope for monoclonal antibody HV-1. These factor V C2-domain mutants should provide valuable tools for further defining the molecular interactions responsible for factor V binding to phospholipid membranes. |
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Bibliography: | istex:965127CED2FFCF5CA039D6DB9C22A5B6D672BE45 This work was supported by grants HL43106 and HL54939 from the National Institutes of Health. ark:/67375/TPS-5N0NMTSC-Z ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi992256r |