pH-sensitive transport of Fe2+ across purified brush-border membrane from mouse intestine.
Recent studies of Fe2+ uptake by mouse proximal intestine brush-border membrane vesicles revealed low-affinity, NaCl-sensitive and high-affinity, NaCl-insensitive, components of uptake (Simpson, R.J. and Peters, T.J. (1985) Biochim. Biophys. Acta 814, 381-388). In this study, the former component is demonstrated to show a strong pH dependence with an optimum of pH 6.8-6.9. Studies at pH 6.5, where the low affinity component is inhibited by more than 25-fold compared with pH 7.2, suggest that the pH-sensitive component represents transport across the brush-border membrane followed by intravesicular binding. Cholate extracts of brush-border membrane vesicles contain pH- and NaCl-sensitive Fe2+ binding moieties which may be involved in the transfer of Fe2+ across the intestinal brush-border membrane and subsequent binding inside the vesicles. Fe2+ uptake by brush-border membrane vesicles from the duodenum of hypoxic mice is higher than uptake by vesicles from control-fed animals, suggesting the existence of a regulable brush-border membrane Fe2+ carrier.
D000222:Adaptation, Physiological; D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology; D005296:Ferrous Compounds / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D008297:Male; D051379:Mice; D008871:Microvilli / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology
D002793:Cholic Acids; D005296:Ferrous Compounds; D012965:Sodium Chloride; D007501:Iron; D019826:Cholic Acid