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Abstract:
1. Earlier work has demonstrated that (a) isolated brush border membranes from rat kidney cortex possess a high-affinity receptor for phlorizin; binding is dependent upon the presence of sodium and is competitively blocked by d-glucose, (b) phlorizin competitively inhibits active transport of glucose across rat kidney proximal tubules and (c) a series of phlorizin-like compounds possess a characteristic, wide range of inhibitory potency as glucose transport poisons in kidney and intestinal systems.
2. 3H-labeled phlorizin binding to the brush border membrane site has now been shown to be inhibited by this series of phlorizin analogs, and the critical finding is that the previosuly established relative potencies of these compounds as transport inhibitors parallel their ability to block phlorizin binding to the specific membrane receptor.
3. These results increase the weight of evidence for the view that the glucose-transport system is retained as a structurally unaltered component of these isolated brush border fragments.
4. A view of the conformation, which the phlorizin receptor could assume in the matrix of the outer membrane, is presented in the discussion.
