Information Flow Through the Plasma Membrane
Via a Membrane Receptor
Shown to the right is an animation intended to illustrate how information, arriving at a cell in the form of chemical messenger (the ligand, shown in red), is perceived by a transmembrane protein ( the receptor, shown in yellow) and how the ligand binding event on the outer surface of the cell changes the conformation of the receptor domain exposed to the cytoplasm such that a specific inactive enzyme can bind to the receptor and become active. Thus, the information that arrived in the form of a ligand is transfered into the cell's cytoplasm as enzymatic activity. Note that when the ligand is removed from the receptor the cytoplasmic enzyme becomes inactive and can no longer bind to the cytoplasmic exposure of the receptor.