Homeostasis cells and muscle cells. The liver is inhibited from producing glucose, taking it up instead, and converting it to glycogen and triglycerides. The glycogen is stored in the liver, but the triglycerides are secreted into the blood as very low-density lipoprotein (VLDL) particles which are taken up by adipose tissue, there to be stored as fats. The fat cells take up glucose through special glucose transporters (GLUT4), whose numbers in the cell wall are increased as a direct effect of insulin acting on these cells. The glucose that enters the fat cells in this manner is converted into triglycerides (via
Glycogen phosphorylase concentration, as the liver acts as a glucose exporter. In essence, liver phosphorylase is responsive to glucose, which causes a very responsive transition from the R to T form, inactivating it; furthermore, liver phosphorylase is insensitive to AMP. Glycogen phosphorylase was the first allosteric enzyme to be discovered. This accomplishment was one of many landmark achievements made by Carl and Gerty Cori. In 1943, with the help of Arda Green, the pair illustrated that glycogen phosphorylase existed in either the or b forms depending on its phosphorylation state, as well as in the R or T states based on the