以放射配基法比较四种培养细胞LDL受体活性

COMPARASION OF LDL RECEPTOR ACTIVITY ON VARIOUS CULTURED CELLS BY RADIOLIGAND ANALYSIS

低密度脂蛋白(LDL)受体在脂代谢调控及动脉粥样硬化中起关键作用。笔者建立的放射配基测定法实用、可靠、精密度高,以此比较了人胚肺成纤维细胞,人胚皮肤成纤维细胞,恒河猴胚肾上皮细胞和猴内皮细胞的 LDL 受体活性,可作为研究 LDL受体活性及影响因素的重要手段。

There are increasing evidences that the low density lipoprotein(LDL)receptor plays a key role in lipid metabolism and pathogenesis of atherosclerosis.The activity of LDL receptor on four kinds of cultured cells was compared by means of radio- ligand analysis,Human serum LDL was isolated by density gradient ultracentrifug- ation and was radioiondinated with (125)~I by method of iodine monoehloride.The maximal high affinity binding (B_(max))of the LDL receptor on human skin fibroblasts was 47 ng/mg cell protein,the apparent K_m value was 9.4μg/ml.The B_(max) and K_m of LDL recpetor on rhesus epithelial cells was 17.8 ng/mg cell protein and 42.7μg/ml, respectively,When human skin fibroblasts,human lung fibroblasts,nrhesus epithelial cells aud rhesus endotheliocytes are incubated with same concentration of (125)~I-LDL; difference among receptor-mediated binding,internalization and degradation of these cells are not significant.The radio-ligand analysis of LDL receptor is of great value in investigation of mechanism of lipid metabolism and pathogenesis of atheroselerosis.