ABSTRACT
Insulin is one of the best-studied hormones. The main actions of insulin are to stimulate the synthesis of glycogen, lipids, and proteins, through modulation of the metabolic pathways implicated in these processes, and the stimulation of cell growth. Insulin has been reported to promote the phosphodiesteratic hydrolysis of a novel glycosyl phosphatidylinositol (glycosyl-PI) in a number of cells, including intact murine BC3H1 myocytes, H35 hepatoma cells, T lymphocytes, and CHO cells. In addition, the polar headgroup of the insulin-sensitive glycosyl-PI isolated from rat liver membranes or H35 hepatoma cells has been shown to contain galactose and up to three additional phosphates, probably linked to a galactose residue through a monoester bond. The majority of the insulin-sensitive glycosyl-PI is present in the plasma membrane and, as with most glycolipids, the bulk of it seems to be present at the outer surface of rat hepatocytes and adipocytes.
