1,25-Dihydroxyvitamin D3 receptors in rat kidney cytosol

Rat kidney cytosol contains a 3.3 S high affinity binding component for 1,25-dihydroxyvitamin D₃ as detected by DNA-cellulose chromatography and subsequent sucrose gradient analysis. The semipurified aporeceptor demonstrates specificity for 1,25-dihydroxyvitamin D₃ and an apparent dissociation constant for this sterol-hormone of 3.4 × 10^?10M at 25°C. The physicochemical properties of this binding component are in agreement with those observed for the chick intestinal 1,25-dihydroxyvitamin D₃ receptor, suggesting that this component may function as a specific receptor for the hormone in the kidney.