02774nas a2200313   4500008004100000245014600041210006900187300001300256490000800269520115600277653004801433653003001481653005001511653023501561653012201796653010201918653014402020100002002164700001502184700002102199700002202220700001702242700002402259700001302283700002002296700001902316700001902335856010602354       2002                        eng d00aUse of single point mutations in domain I of beta 2-glycoprotein I to determine fine antigenic specificity of antiphospholipid autoantibodies0 aUse of single point mutations in domain I of beta 2glycoprotein   a7097-1030 v1693 aAutoantibodies against beta(2)-glycoprotein I (beta(2)GPI) appear to be a critical feature of the antiphospholipid syndrome (APS). As determined using domain deletion mutants, human autoantibodies bind to the first of five domains present in beta(2)GPI. In this study the fine detail of the domain I epitope has been examined using 10 selected mutants of whole beta(2)GPI containing single point mutations in the first domain. The binding to beta(2)GPI was significantly affected by a number of single point mutations in domain I, particularly by mutations in the region of aa 40-43. Molecular modeling predicted these mutations to affect the surface shape and electrostatic charge of a facet of domain I. Mutation K19E also had an effect, albeit one less severe and involving fewer patients. Similar results were obtained in two different laboratories using affinity-purified anti-beta(2)GPI in a competitive inhibition ELISA and with whole serum in a direct binding ELISA. This study confirms that anti-beta(2)GPI autoantibodies bind to domain I, and that the charged surface patch defined by residues 40-43 contributes to a dominant target epitope.10aAmino Acid Substitution/genetics Antibodies10aAntibody/genetics Binding10aAntiphospholipid/blood/*metabolism Antibodies10aCompetitive/genetics/immunology Enzyme-Linked Immunosorbent Assay/methods Epitopes/analysis/*immunology/metabolism Glycine/genetics Glycoproteins/biosynthesis/*genetics/*immunology/isolation & purification/metabolism Humans Models10aMolecular Peptide Fragments/genetics/immunology/isolation & purification/metabolism *Point Mutation Protein Structure10aMonoclonal/blood/metabolism Antiphospholipid Syndrome/immunology Arginine/genetics *Binding Sites10aTertiary/genetics Recombinant Proteins/biosynthesis/immunology/isolation & purification/metabolism Static Electricity beta 2-Glycoprotein I1 aIverson, G., M.1 aReddel, S.1 aVictoria, E., J.1 aCockerill, K., A.1 aWang, Y., X.1 aMarti-Renom, M., A.1 aSali, A.1 aMarquis, D., M.1 aKrilis, S., A.1 aLinnik, M., D.  uhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=12471146