2×10^12 to 2×10^14 binding sites/mg placental membrane protein
||Human Homo sapiens
||Saji F, Samejima Y, Kamiura S, Koyama M. Dynamics of immunoglobulins at the feto-maternal interface. Rev Reprod. 1999 May4(2):81-9 p.81 right column bottom paragraphPubMed ID10357095
||McNabb T, Koh TY, Dorrington KJ, Painter RH. Structure and function of immunoglobulin domains. V. Binding of immunoglobulin G and fragments to placental membrane preparations. J Immunol. 1976 Sep117(3):882-8 AND Brown PJ, Johnson PM. Fc gamma-receptor activity of isolated human placental syncytiotrophoblast plasma membrane. Immunology. 1981 Feb42(2):313-9 AND Niezgódka M, Mikulska J, Ugorski M, Boratyński J, Lisowski J. Human placental membrane receptor for IgG-I. Studies on properties and solubilization of the receptor. Mol Immunol. 1981 Mar18(3):163-72 AND Lubega J. A kinetic study of human IgG binding to placental Fc gamma-receptor. Mol Immunol. 1990 Jan27(1):45-55PubMed ID956658, 7461733, 7266485, 2138245
||Primary source Brown and Johnson, 1981, abstract: "Fc gamma-receptor activity of isolated human placental syncytiotrophoblast microvillous plasma membrane (StMPM) vesicle preparations has been determined in an immunoradiometric assay using Sepharose-immobilized protein A to separate free 125I-labelled human IgG from membrane-bound 125I-IgG…Inhibition studies have determined the syncytiotrophoblast Fc gamma-receptor equilibrium constant for association (Ka) as 4.0×10^7 M^-1 at 37 degrees and the number of available Fc gamma-receptor sites as 1.5×10^14 per mg membrane protein." Primary source Lubega, 1990, abstract: "Various methods for studying the IgG interaction with its placental receptor have been examined to establish kinetic parameters."
||P.81 right column bottom paragraph: "Various methods have been used to investigate IgG-binding molecules, such as FcγRs, in placenta. Most of them used the analysis of the binding of isolated human placental membrane extracts to radiolabelled human IgG or IgG-sensitized erythrocytes. Estimates of the affinity of monomeric IgG for receptors in placental membrane range from 4×10^6 to 4×10^8 mol/l and a total number of binding sites per mg placental membrane protein ranges from 2×10^12 to 2×10^14 (primary sources)." Primary source McNabb et al., 1976, abstract: "Fc from IgG1 bound with the same affinity as the whole molecule and to the same number of receptor sites, 2×10^12/mg placental protein." Primary source Brown and Johnson, 1981, abstract: "Inhibition studies have determined the syncytiotrophoblast Fc gamma-receptor equilibrium constant for association (Ka) as 4.0×10^7/M at 37 degrees and the number of available Fc gamma-receptor sites as 1.5×10^14 per mg membrane protein." Primary source Lubega, 1990, abstract: "IgG binding was associated with a high average affinity of (3.70 +/- 1.65)×10^8/M and a total number of receptor binding sites of (2.07 +/- 0.93)×10^14 sites/mg of membrane protein, in close agreement with previous results." Please note-titles of primary sources in article and in PUBMED vary slightly: the PUBMED versions appear herein