Signaalinvälitysreaktio

Signaalinvälitysreaktio, known in English as signal transduction, is the process by which a cell responds to a stimulus. This stimulus, or signal, can originate from outside the cell, such as a hormone or neurotransmitter, or from within the cell itself. The signal initiates a series of molecular events that ultimately lead to a specific cellular response.

This complex process typically involves several key stages. First, a signaling molecule, or ligand, binds to a specific receptor on the cell surface or within the cell. This binding event triggers a conformational change in the receptor, activating it. The activated receptor then initiates a cascade of intracellular events, often involving a series of protein phosphorylations or other modifications. These molecular switches amplify the initial signal and relay it to various cellular targets.

Ultimately, these intracellular signaling pathways lead to a change in cellular behavior. This response can take many forms, including changes in gene expression, enzyme activity, cell growth and division, or movement. Signal transduction is crucial for a vast array of biological processes, from basic cellular functions to complex physiological responses like muscle contraction and immune system activation. Dysregulation of signal transduction pathways can contribute to various diseases, including cancer and diabetes, making them important targets for therapeutic intervention.