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:5926800

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: 5926800
• 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

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BINDING ENERGY
BIRDS
BODY
CELL CONSTITUENTS
CENTRIFUGATION
CHEMICAL PROPERTIES
CHICKENS
CHOLECALCIFEROL
CYTOPLASM
DIGESTIVE SYSTEM
ENERGY
FOWL
GASTROINTESTINAL TRACT
HYDROGEN ISOTOPES
INTESTINES
ISOTOPES
LIGHT NUCLEI
MAMMALS
MUCOUS MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RATS
RODENTS
SEPARATION PROCESSES
TRITIUM
ULTRACENTRIFUGATION
VERTEBRATES
VITAMIN D
VITAMINS
YEARS LIVING RADIOISOTOPES