CHOLESTEROL-INDEPENDENT TARGETING OF GOLGI MEMBRANE-PROTEINS IN INSECT CELLS

Distinct lipid compositions of intracellular organelles could provide a physical basis for targeting of membrane proteins, particularly wher e transmembrane domains have been shown to play a role. We tested the possibility that cholesterol is required for targeting of membrane pro teins to the Golgi complex. We used insect cells for our studies becau se they are cholesterol auxotrophs and can be depleted of cholesterol by growth in delipidated serum. We found that two well-characterized m ammalian Golgi proteins were targeted to the Golgi region of Aedes alb opictus cells, both in the presence and absence of cellular cholestero l. Our results imply that a cholesterol gradient through the secretory pathway is not required for membrane protein targeting to the Golgi c omplex, at least in insect cells.