Versterking van signalen via tweede boodschappers

Second messengers are low molecular weight non-protein molecules that relay signals to targets within the cell when ligands bind to receptors on the cell surface.

Second messengers include ions, such as calcium ions; cyclic nucleotides, such as cyclic AMP; and small molecules, such as phosphatidylinositol phosphate derivatives diacylglycerol or DAG and inositol trisphosphate or IP₃.

Calcium ions are a widely occurring second messenger. The intracellular calcium concentration increases in response to specific signals and triggers diverse physiological functions. For example, in muscle cells, an increase in cytosolic calcium results in muscle contraction.

Different G-protein coupled receptor families activate enzymes that generate second messengers, including adenylyl cyclase which produces cyclic AMP and phospholipase C which produces DAG and IP₃.

These second messengers can activate multiple downstream kinases, further amplifying the signal.