The receptor interacts with outside signals and transmits them to the inside. Ligands are extracellular proteins or other molecules that interact with a receptor to cause it to transmit a signal to the inside of the cell. Notch is a receptor that receives signals from its ligands and transmits these signals to the inside of the cell. The Notch pathway consists of Notch and its ligands, as well as intracellular proteins that transmit the Notch signal to the nucleus. Included in the pathway are transcription factors, the proteins that bear the effector function of the pathway.
Lateral inhibition occurs repeatedly in Drosophila development.
Central to this process is the interaction of Notch receptor with a group of ligands including Delta , Scabrous and Serrate . Some of these ligands float free around the outside of the cell and others are bound to the surface of cells. The interaction of Notch with its ligand triggers a chain of intracellular events resulting in lateral inhibition, the prevention of a specified fate committment on the part of most of the cells of a cluster. The first link in the chain of events is a reduction of the affinity of Suppressor of Hairless protein for the cytoplasmic tail of the Notch receptor. This complex will then inhibit the proneural genes achaete , scute , lethal of scute and asense .