Widespread, specific binding of 25 hydroxycholecalciferol in rat tissues

J. G. Haddad, S. J. Birge

Research output: Contribution to journalArticle

64 Scopus citations

Abstract

In the vitamin D depleted rat, all nucleated tissues examined (brain, lung, heart, pancreas, liver, cartilage, muscle, bone, kidney, and intestine) contained a soluble substance which bound 25 hydroxy[3H]cholecalciferol in vitro specifically and sedimented at 6.3 S in linear sucrose gradients. The serum steroid complex sedimented a 4.1 S, and erythrocyte lysates were apparently devoid of specific binding activity. The ability of these cytosols to specifically bind the steroid was destroyed by treatment with trypsin, but not by RNase, DNase, or 1 mM p hydroxymercuribenzoate. The sedimentation pattern was not altered in sucrose gradients containing 0.5 M KCl or following cytosol preparation and ultracentrifugation in gradients containing 0.012 M dithiothreitol. The apparent avidity for 25 hydroxycholecalciferol (K(A) 2 x 10-9 M) was slightly higher in muscle and kidney cytosols than in serum, but serum contained a large number of specific binding sites. The presence of widespread, high affinity binding proteins for 25 hydroxycholecalciferol raises the possibility that tissues other than the intestine, bone, and kidney may respond directly to vitamin D metabolites.

Original languageEnglish
Pages (from-to)299-303
Number of pages5
JournalJournal of Biological Chemistry
Volume250
Issue number1
StatePublished - Jan 1 1975

Fingerprint Dive into the research topics of 'Widespread, specific binding of 25 hydroxycholecalciferol in rat tissues'. Together they form a unique fingerprint.

  • Cite this