Notes: Here the authors examined the intracellular cholesterol esterification enzyme acyl-CoA:cholesterol acyltransferase (ACAT) present in the nonhuman primate hepatocyte. AC29 cells, Chinese hamster ovary cells that lack ACAT activity, at 80% confluence in 100mm dishes were transfected with 5µg of ACAT1 and ACAT2 cDNA vectors using 10µl of FuGENE® 6 Transfection Reagent. After 48 hours, the cells were harvested by scraping, sonicated and ACAT activity assessed either in cell homogenates or isolated microsomes. ACAT1 and ACAT2 vectors were linearized for transcription with T7 RNA polymerase and translation using rabbit reticulocyte lysate and canine pancreas microsomes; the translated protein was radiolabeled with [³⁵S]methionine. The protein products were analyzed using 12.5% SDS- PAGE and autoradiography. (4294)