Insulin signal transduction pathway signals the conversion of the glycogen already stored in the liver cells into glucose. This process is called glycogenolysis. Conversely, when the blood-glucose levels are too high, the pancreas is signaled to release insulin. Insulin is delivered to the liver and other tissues throughout the body (e.g., muscle, adipose). When the insulin is introduced to the liver, it connects to the insulin receptors already present, that is tyrosine kinase receptor. These receptors have two alpha subunits (extracellular) and two beta subunits (intercellular) which are connected through the cell membrane via disulfide bonds. When the insulin binds to these alpha subunits,
Lifestyle causes of diabetes mellitus type 2 that "produce fewer and smaller mitochondria than is normal," and are thus prone to insulin resistance. Fat tissue has also been shown to be involved in managing much of the body's response to insulin and control of uptake of sugar. It secretes RBP4 which increases insulin resistance by blocking the action of insulin in muscle and liver. Fat cells also secrete adiponectin which acts in an opposite way to RBP4 by improving the action of insulin, however, engorged fat cells secrete it in lower amount than normal fat cells. The obese therefore may have higher level of RBP4 but lower