The Molecules That Transmit Information into the Cell: The Intracellular Signaling Pathways

Extracellular regulatory molecules convey information into the cell through a fast low energy complex of signals known as intracellular signaling pathways. The function of the pathways is to organize and amplify the signals in a way that a small number of ligands bound to receptors affect the activity of a large number of intracellular molecules. Signaling molecules can be divided into two main groups: the intracellular messengers and homology domain proteins.