The mechanisms of proteolytic processing of precursor proteins and the evolution of insulin-like hormones and their receptors are related topics of interest.
Many hormones interact to integrate body growth with nutrition and other intrinsic signals.
The islets of Langerhans, small cell clusters composed of several kinds of specialized endocrine cells, secrete several hormones that play a critically important role in regulating fuel metabolism. The most prominent of these are insulin and glucagon, which together act to maintain normal levels of blood glucose. Insulin promotes glucose utilization by tissues and therefore tends to lower the blood glucose level, while glucagon tends to raise it by increasing liver glycogen breakdown and the neosynthesis of glucose from protein. When insulin is not secreted in sufficient amounts or there are defects in its action, the blood sugar becomes elevated and diabetes results. These precursors contain additional portions that help to guide them along special intracellular channels to be stored in vesicles and processed into their biologically active forms.