Intestinal cytosol binders of 1,25-dihydroxyvitamin D/sub 3/ and 25-hydroxyvitamin D/sub 3/

Journal Article · Thu Jan 01 04:00:00 EST 1976 · Arch. Biochem. Biophys.; (United States)

DOI:https://doi.org/10.1016/0003-9861(76)90222-8· OSTI ID:7277180

Kream, B E; Reynolds, R D; Knutson, J C; Eisman, J A; DeLuca, H F

The binding of 25-hydroxy-(26,27-/sup 3/H)vitamin D/sub 3/ and 1,25-dihydroxy-(26,27-/sup 3/H)vitamin D/sub 3/ to the cytosol of intestinal mucosa of chicks and rats has been studied by sucrose gradient analysis. The cytosol from chick mucosa showed variable binding of 1,25-dihydroxyvitamin D/sub 3/ to a 3.0S macromolecule which has high affinity and low capacity for this metabolite. However, when the mucosa was washed extensively before homogenization, a 3.7S macromolecule was consistently observed which showed considerable specificity and affinity for 1,25-dihydroxyvitamin D/sub 3/. Although 3.7S binders for 1,25-dihydroxyvitamin D/sub 3/ could also be located in other organs, competition experiments with excess nonradioactive 1,25-dihydroxyvitamin D/sub 3/ suggested that they were not identical to the 3.7S macromolecule from intestinal mucosal cytosol. As the 3.7S macromolecule was allowed to stand at 4/sup 0/C with bound 1,25-dihydroxy-(/sup 3/H)vitamin D/sub 3/, the 1,25-dihydroxy-(/sup 3/H)vitamin D/sub 3/ became increasingly resistant to displacement by nonradioactive 1,25-dihydroxyvitamin D/sub 3/. The 1,25-dihydroxy-(/sup 3/H)vitamin D/sub 3/ remained unchanged and easily extractable with lipid solvents through this change, making unlikely the establishment of a covalent bond. Unlike the chick, mucosa from rats yielded cytosol in which no specific binding of 1,25-dihydroxy-(/sup 3/H)vitamin D/sub 3/ was detected. Instead, a 5-6S macromolecule which binds both 1,25-dihydroxyvitamin D/sub 3/ and 25-hydroxyvitamin D/sub 3/ was found. This protein which was also found in chick mucosa shows preferential binding for 25-hydroxyvitamin D/sub 3/. It could be removed by washing the mucosa with buffer prior to homogenization which suggests that it may not be a cytosolic protein. Although the 3.7S protein from chick mucosa has properties consistent with its possible role as a receptor, the 5-6S macromolecule does not appear to have ''receptor''-like properties.

• Research Organization: Univ. of Wisconsin, Madison
• OSTI ID: 7277180
• Journal Information: Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 176; ISSN ABBIA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550500 -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BIRDS
BODY
CENTRIFUGATION
CHEMICAL REACTIONS
CHEMISTRY
CHICKENS
CHOLECALCIFEROL
CHROMATOGRAPHY
COMPLEXES
DIGESTIVE SYSTEM
FOWL
GASTROINTESTINAL TRACT
HYDROGEN ISOTOPES
INTESTINES
ISOTOPES
LIGHT NUCLEI
MAMMALS
METABOLISM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RATS
RODENTS
SEPARATION PROCESSES
TRITIUM
ULTRACENTRIFUGATION
VERTEBRATES
VITAMIN D
VITAMINS
YEARS LIVING RADIOISOTOPES