A specific high-affinity binding macromolecule for 1,25-dihydroxyvitamin D3 in fetal bone

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Science  09 Sep 1977:
Vol. 197, Issue 4308, pp. 1086-1088
DOI: 10.1126/science.887939


Cytosol fractions were prepared from fetal rat or embryonic chick calvaria and analyzed for binding of vitamin D3 metabolites on sucrose density gradients. Both cytosol fractions contain a 3.5S macromolecule which specifically binds 1,25-dihydroxy-[3H]vitamin D3 and in addition, a 5 to 6S macromolecule which binds 25-hydroxy-[3H]vitamin D3. In rat calvaria cytosol, 1,25-dihydroxy-[3H]vitamin D3 also binds to the 5 to 6S macromolecule but appears to have greater affinity for the 3.5S component.