title: Characterization of the transferrin-binding protein in a human trophoblast.
abstract: The physical properties and binding characteristics of the solubilized transferrin-binding protein from BeWo cells, a human choriocarcinoma cell line, were investigated. The binding protein was isolated from 125I-labelled membranes by solubilization followed by immunoprecipitation with anti-human transferrin in the presence of saturating human transferrin. Gel filtration on acrylamide agarose (AcA-22) at 21 degrees C in the absence of transferrin indicates that the transferrin-binding protein has a Stokes' radius of 4.6 nm. In the presence of transferrin, the Stokes' radius of the transferrin-binding BeWo protein increases to 6.3 nm. Parallel sucrose density centrifugation studies indicate that the BeWo protein has a sedimentation coefficient of 9.4 S in the absence of transferrin and 10.9 S in the presence of transferrin. Relative molecular mass calculations from sedimentation studies in H2O and D2O, using the method of Sadler et al (1979), indicate a relative molecular mass of 204,000 for the solubilized receptor and 354,000 for the receptor in the presence of transferrin.
mesh_terms: D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D002845:Chromatography; D005260:Female; D006801:Humans; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology; D011247:Pregnancy; D011956:Receptors, Cell Surface / Q000032:analysis*; D011990:Receptors, Transferrin; D014327:Trophoblasts / Q000032:analysis*
chemical_list: D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; D011092:Polyethylene Glycols; D017830:Octoxynol