Professor - Emeritus
B.S., 1960 Lawrence College;
M.D., 1964 Harvard Medical School
My long-term research interest is in membrane biochemistry. Over the years, I have studied the molecular organization of the human red cell membrane and the membrane biology of the ameba, Dictyostelium discoideum. In addition, the disposition of cell cholesterol has been a recurrent focus. We are currently investigating cellular cholesterol homeostasis: how cells sense their need for this essential plasma membrane lipid and make appropriate adjustments to keep it in balance. We suggest that cells gauge the magnitude of the bulk pool of cholesterol in the plasma membrane by sensing the high activity of the cholesterol in excess of phospholipid partners. This active excess sets the size of the sterol pool in the endoplasmic reticulum and mitochondria through the flow of cholesterol between the cell surface and intracellular membranes. The endoplasmic reticulum and mitochondrial pools then set the level of activity of several regulatory elements in those membranes that then mediate sterol homeostasis. The elements of this cholesterol sensing system and how it can be manipulated are under investigation.