Binding Proteins for 1, 25-Dihydroxychole-Carciferol and 25-Hydroxy-Cholecarciferol

Abstract

The proteins participating in translocation of vitamin D3 metabolites inside the cell of the rat intestinal mucosa were identified by sucrose density gradient ultracentrifugation. Sixteen hours after an intracardial administration of radioactive vitamin D3 (100 I. U.) to the vitamin D deficient rat, 3.5% of the administered radioactivity was distributed in the intestinal mucosa, and about half of this amount in the crude nuclear fraction. In this case, approximately 60% of the radioactivity extracted from the intestinal mucosa was observed to be 1,25-DHCC and about 20% as 25-HCC, respectively. In an addition of radioactive 1,25-DHCC or 25-HCC to the intestinal mucosa in vitro, both 1,25-DHCC and 25-HCC were incorporated into the nuclear fraction of rat intestinal mucosa. However, little of the D3 was found in the nuclei. Furthermore, for transport of vitamin D3 metabolites into the nuclei in cell free system of the rat intestinal mucosa, the presence of the cyto plasmic fraction was found to be essential. Subsequently, the individual binding proteins specific to 1,25-DHCC and 25-HCC were identified in the cytoplasmic fraction of rat intestinal mucosa by means of sucrose density gradient ultracentrifugation.The sedimentation constants of these two proteins were approximately 5.3 and 6.3, respectively. How ever, the binding protein specific to vitamin D3 was not found in the cytoplasmic fraction by sucrose density gradient ultracentrifugation without prior treatment by Sephadex G-200 column chromatography. From these results, it was concluded that the cytoplasmic fraction of rat intestinal mucosa contained the specific binding proteins participat ing in the intracellular translocation of 1,25-DHCC and 25-HCC in rat intestinal mucosa.

Metabolic Fate and Expectation of Health Benefits of [U-¹⁴C]-Sucrose Inhibited from Digestion Using <i>Morus alba</i> Leaf Extract

“…Preparation of test solutions containing [U- 14 C]-sucrose. The test solutions containing [U-14 C]-sucrose were prepared as follows: 159 kBq (4.3 mCi) of [U-14 C]-sucrose and 300 mg of sucrose were dissolved in 2 mL of sterilized water, on the base of our previous experiments (21,(32)(33)(34). The solutions containing both [U-14 C]-sucrose and MLE were prepared as follows: 159 kBq (4.3 mCi) of [U-14 C]-sucrose and 300 mg of sucrose were dissolved in 2 mL of original MLE solution containing 0.24% DNJ equivalents.…”

“…The interior temperature was maintained at 236 1˚C. The excreted 14 CO2, urine, and feces were collected for 24 h after administration of the test solution, as in our previous experiments (21,(32)(33)(34). The rats that were transferred to the glass metabolic apparatus were made to fast for further 6 h and only given drinking water.…”

“…Sample preparation for measuring 14 C-radioactivity was carried out as described in our previous experiments (21,(32)(33)(34). Five hundred microliters of monoethanolamine with trapped 14 CO2 were transferred into a counting vial, and the radioactivity was determined with a liquid scintillation counter (LSC-6000; Aloca Co. Ltd., Tokyo, Japan) after the addition of 5 mL of scintillation cocktail (Hionic-Fluor; Perkin Elmer Japan Co. Ltd., Kanagawa, Japan) and 1 mL of cellosolve (FUJI-FILM Wako Pure Chemical Corporation).…”

Development of 1,25-dihydroxycholecalciferol receptor in the duodenal cytosol of chick embryo.

“…A receptor for 1,25-(OH)2D3 has been demonstrated in the cytosol and nuclei of chick (Lawson and Wilson, 1974;Brumbaugh and Haussler, 1974) and rat intestinal mucosa (Hadded et al, 1973;Oku et al, 1974) from several laboratories.…”