signal transduction

Signal transduction is the process by which cells communicate and respond to external signals. In multicellular organisms, cells coordinate their activities through chemical signaling. These signals, or first messengers, bind to specific receptor proteins, which can be located on the cell surface or within the cytoplasm.

This binding triggers a cascade of events inside the cell. Some receptors activate enzymes that produce intracellular signaling molecules, known as second messengers, like cyclic AMP or calcium ions. These second messengers then modify the cell's behavior, often by activating enzymes called kinases, which can alter protein synthesis or activate target genes. Other receptors may allow signals to enter the cell directly or cause changes in ion flow across the cell membrane. The specific response depends on the type of receptor and the cell involved.123