How do signal transduction pathways occur?

In signal transduction, extracellular signaling molecules—also referred to as ligands—bind to receptors, which in turn cause internal cellular events. When a signaling molecule and a receptor combine, the receptor's conformation changes, a process known as receptor activation.

Signal transduction pathways occur through a series of molecular events triggered by the binding of a signaling molecule (ligand) to a receptor on the cell surface or inside the cell. This binding activates the receptor, initiating a cascade of intracellular events that relay the signal to the target molecules, often resulting in a specific cellular response. These pathways typically involve protein kinases, second messengers, and transcription factors, which mediate signal amplification, integration, and transmission within the cell.