1. The effects of 26-aminocholesterol and 26-thiacholesterol on cholesterol synthesis and LDL (low-density lipoprotein)-receptor activity were compared with naturally occurring 26-hydroxycholesterol utilizing both human fibroblasts and hepatoma (Hep G2) cells. 2. At equimolar concentrations (0.625 microM), down-regulation of LDL-receptor activity and cholesterol synthesis was greater with human fibroblasts than with Hep G2 cells. 3. At much higher concentrations (5-20 microM) the 26-thia analogue had little effect on either cholesterol synthesis or LDL-receptor activity.
