1,25-二羟胆钙化醇在鸡肠道中的核内定位及受体蛋白

Intranuclear localization and receptor proteins for 1,25-dihydroxycholecalciferol in chick intestine.

作者信息

Lawson D E, Wilson P W

出版信息

Biochem J. 1974 Dec;144(3):573-83. doi: 10.1042/bj1440573.

DOI:10.1042/bj1440573

PMID:4377658

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1168536/

Abstract

The intranuclear distribution of cholecalciferol and its metabolites was studied in the intestine of rachitic chicks. 2. At high doses of cholecalciferol the nuclei contain the vitamin and its 25-hydroxy metabolite, but over 80% of this is localized on the nuclear membranes. The hormone, 1,25-dihydroxycholecalciferol, is found within the cell nuclei irrespective of the intake of cholecalciferol, but significant amounts could not be found with chromatin isolated free of nuclear membranes. 3. 1,25-Dihydroxycholecalciferol is associated in the nucleus with an acidic protein. Since one of the actions of 1,25-dihydroxycholecalciferol is to control the synthesis of mRNA for calcium-binding protein it was to be expected that the hormone would be bound to chromatin, as with the other steroid hormones. It is suggested that the hormone-receptor complex exists as part of an equilibrium mixture of the complex bound to the DNA and in a free form. 4. A protein extract of nuclei was obtained, which when incubated at 4 degrees C for 1h took up the 1,25-dihydroxycholecalciferol. The nature of this binding was studied. 5. There appear to be two nuclear proteins able to bind the hormone one of which is the intestinal nuclear receptor. The binding sites on this protein are saturable with the hormone, have an association constant of 2x10(9)m(-1) and show a high chemical specificity for the 1,25-dihydroxycholecalciferol. The number of nuclear binding sites for the hormone provided by this receptor is similar to the maximum intestinal hormone concentration so far observed. Its sedimentation coefficient is 3.5S, and is very close to that observed for the nuclear protein to which is attached the 1,25-dihydroxycholecalciferol formed in vivo from vitamin D. 6. The cytoplasmic protein has an association constant of 1x10(9)m(-1)and a sedimentation coefficient of 3.0S, but its relation with the nuclear receptor is not yet clear.

摘要

研究了维生素D3及其代谢产物在佝偻病雏鸡肠道中的核内分布情况。2. 高剂量维生素D3时，细胞核含有该维生素及其25-羟基代谢产物，但其中80%以上定位于核膜上。激素1,25-二羟基维生素D3无论维生素D3摄入量如何，均可在细胞核内发现，但在不含核膜的分离染色质中未发现大量该激素。3. 1,25-二羟基维生素D3在细胞核内与一种酸性蛋白相关。由于1,25-二羟基维生素D3的作用之一是控制钙结合蛋白mRNA的合成，因此预期该激素会像其他甾体激素一样与染色质结合。有人提出激素-受体复合物以与DNA结合的复合物和游离形式的平衡混合物的一部分存在。4. 获得了细胞核的蛋白提取物，将其在4℃孵育1小时可摄取1,25-二羟基维生素D3。研究了这种结合的性质。5. 似乎有两种核蛋白能够结合该激素，其中一种是肠核受体。该蛋白上的结合位点可被激素饱和，结合常数为2×10⁹m⁻¹，对1,25-二羟基维生素D3表现出高度化学特异性。该受体提供的激素核结合位点数量与迄今为止观察到的最大肠激素浓度相似。其沉降系数为3.5S，与体内由维生素D形成的1,25-二羟基维生素D3所附着的核蛋白的沉降系数非常接近。6. 细胞质蛋白的结合常数为1×10⁹m⁻¹，沉降系数为3.0S，但其与核受体的关系尚不清楚。