STUDIES ON ORGANIZATION OF BRUSH BORDER IN INTESTINAL EPITHELIAL CELLS .6. GLUCOSE BINDING TO ISOLATED INTESTINAL BRUSH BORDERS AND THEIR SUBFRACTIONS

A sensitive method for the measurement of specific glucose binding to isolated hamster intestinal brush borders has been developed. The method is based on the difference in binding of l-[14C]glucose and d-(su3H]glucose as measured by retention of radioactivity on Millipore filters. Properties of the binding have been studied. Binding appears to be localized to brush borders. It exhibits a specificity towards a variety of test sugars which is different from the specificity of intestinal active transport. The Km of binding is 2 μM. Binding to intact brush borders shows no requirement for Na+. Binding is inhibited by Ca2+, Co2+, Fe2+, and Zn2+ and activated by Mg2+ and Mn2+. Binding to brush borders is highest in the distal portion of the small intestine. The distribution of binding among subfractions of the brush border has been studied. Possible interpretations of this binding are discussed. © 1969.