Subcellular distribution of DNA-binding and non-DNA-binding 1,25-dihydroxyvitamin D receptors in chicken intestine.

A comparison of 1,25-dihydroxyvitamin D3 receptor concentration and equilibrium dissociation constants of whole tissue, nuclear, and cytosol extracts of vitamin D-deficient chicken intestine has been carried out. The extracts had the following order of receptor concentration: nuclei greater than whole tissue greater than cytosol. The receptors in each preparation had identical equilibrium dissociation constants (Kd) for 1,25-dihydroxyvitamin D3. However, the receptor in the cytosol fraction did not bind to DNA-cellulose, while a large fraction of the receptor population in crude nuclear extract and whole tissue extract bound to DNA-cellulose and could be eluted with 0.22 M KCl, suggesting that the cytosolic form of the receptor does not possess a DNA binding site.