Signal transduction

Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a <a href="/facts/Biochemical_cascade/bCsA7XXG">series of molecular events</a>. Proteins responsible for detecting stimuli are generally termed <a href="/facts/Receptor_(biology)/tjTAC76a">receptors</a>, although in some cases the term sensor is used. The changes elicited by <a href="/facts/Ligand_(biochemistry)/44QLL4eU">ligand</a> binding (or signal sensing) in a receptor give rise to a <a href="/facts/Biochemical_cascade/bCsA7XXG">biochemical cascade</a>, which is a chain of biochemical events known as a <a href="/facts/Cell_signaling/6oYAVP9I">signaling pathway</a>.
When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events. At the molecular level, such responses include changes in the <a href="/facts/Transcription_(biology)/bDgp9HDN">transcription</a> or <a href="/facts/Translation_(biology)/JcPC1rth">translation</a> of genes, and <a href="/facts/Post-translational_modification/KMUayTIc">post-translational</a> and conformational changes in proteins, as well as changes in their location. These molecular events are the basic mechanisms controlling <a href="/facts/Cell_growth/wbArMaJU">cell growth</a>, proliferation, <a href="/facts/Metabolism/WxDrm8k5">metabolism</a> and many other processes. In multicellular organisms, signal transduction pathways regulate <a href="/facts/Cellular_communication_(biology)/6oYAVP9I">cell communication</a> in a wide variety of ways.
Each component (or node) of a signaling pathway is classified according to the role it plays with respect to the initial stimulus. <a href="/facts/Ligand_(biochemistry)/44QLL4eU">Ligands</a> are termed first messengers, while receptors are the signal transducers, which then activate primary effectors. Such effectors are typically proteins and are often linked to <a href="/facts/Second_messenger/J0eEENxQ">second messengers</a>, which can activate secondary effectors, and so on. Depending on the efficiency of the nodes, a signal can be amplified (a concept known as signal gain), so that one signaling molecule can generate a response involving hundreds to millions of molecules. As with other signals, the transduction of biological signals is characterised by delay, noise, signal feedback and feedforward and interference, which can range from negligible to pathological. With the advent of <a href="/facts/Computational_biology/GxgNfwcX">computational biology</a>, the <a href="/facts/Systems_biology/HTH1z1RA">analysis</a> of signaling pathways and networks has become an essential tool to understand cellular functions and <a href="/facts/Disease/55eeQlGL">disease</a>, including signaling rewiring mechanisms underlying responses to acquired drug resistance.

Signal transduction open-in-new

Signal transduction