Cholate-soluble and -insoluble iron binding components of rabbit duodenal brush-border membrane. Relevance to Fe2+ uptake by brush-border membrane vesicles.
Fe2+ uptake by brush-border membrane vesicles from rabbit duodenum has been investigated and found to show similar qualitative properties to those previously demonstrated with mouse proximal intestine brush-border membrane vesicles (Simpson, R.J. and Peters, T.J. (1986) Biochim. Biophys. Acta 856, 109-114). In particular, a relatively low affinity (Km(app) approx. 83 microM), NaCl and pH sensitive transport component is present. The disruption of 59Fe2+-laden vesicles with sodium cholate, followed by gel filtration or centrifugal analysis reveals that cholate insoluble material (Mr greater than 10(6)) is the major destination for 59Fe2+ taken up by intact vesicles. Analysis of cholate extracts for Fe2+ binding ability reveals a single high-capacity (49.8 +/- 15.6 nmol/mg vesicle protein (S.E., n = 3)), high-affinity (Kd(app) less than 5 microM) binding component with an Mr equivalent to approx. 10(4) on gel filtration in the presence of cholate. This binding component is extracted into chloroform/methanol (2:1, v/v) is relatively heat and protease resistant and thus appears to be a lipid.
D000818:Animals; D001665:Binding Sites; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology*; D002850:Chromatography, Gel; D004386:Duodenum / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007501:Iron / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism*; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000494:pharmacology; D011817:Rabbits; D012995:Solubility
D002793:Cholic Acids; D007501:Iron; D010447:Peptide Hydrolases; D019826:Cholic Acid