CELL SIGNALLING
Cell Signaling. Cells typically communicate using chemical signals. These chemical signals, which are proteins or other molecules produced by a sending cell , are often secreted from the cell and released into the extracellular space. There, they can float over to neighboring cells. Not all cells can “hear” a particular chemical message. To detect a signal (that is, to be a target cell ), a neighbor cell must have the right receptor for that signal. When a signaling molecule binds to its receptor, it alters the shape or activity of the receptor, triggering a change inside of the cell. Signaling molecules are often called ligands , a general term for molecules that bind specifically to other molecules (such as receptors). The message carried by a ligand is often relayed through a chain of chemical messenger...