signal transduction

Definition

Target type: biologicalprocess

The cellular process in which a signal is conveyed to trigger a change in the activity or state of a cell. Signal transduction begins with reception of a signal (e.g. a ligand binding to a receptor or receptor activation by a stimulus such as light), or for signal transduction in the absence of ligand, signal-withdrawal or the activity of a constitutively active receptor. Signal transduction ends with regulation of a downstream cellular process, e.g. regulation of transcription or regulation of a metabolic process. Signal transduction covers signaling from receptors located on the surface of the cell and signaling via molecules located within the cell. For signaling between cells, signal transduction is restricted to events at and within the receiving cell. [GOC:go_curators, GOC:mtg_signaling_feb11]

Signal transduction is a complex process by which cells receive and respond to signals from their environment. It involves a series of steps that begin with the binding of a signaling molecule to a specific receptor protein on the cell surface or inside the cell. This binding event triggers a chain of events that ultimately leads to a cellular response.

The first step in signal transduction is the reception of the signal. Signaling molecules, also known as ligands, can be hormones, neurotransmitters, growth factors, or other molecules that bind to specific receptors on the cell surface or inside the cell. The binding of a ligand to its receptor activates the receptor, initiating a cascade of intracellular events.

Once the receptor is activated, it initiates a signaling pathway. Signaling pathways involve a series of molecular interactions that transmit the signal from the receptor to the target molecule within the cell. This pathway can involve multiple protein kinases, second messengers, and other signaling molecules.

Signal transduction pathways can be categorized into different types, including G protein-coupled receptor (GPCR) pathways, receptor tyrosine kinase (RTK) pathways, and ion channel-linked pathways. Each pathway involves specific proteins and mechanisms for signal transmission.

GPCR pathways are involved in a wide range of cellular processes, including vision, olfaction, and hormone signaling. They involve a seven-transmembrane receptor, a G protein, and an effector protein. When a ligand binds to the GPCR, it activates the G protein, which in turn activates the effector protein, leading to the production of a second messenger.

RTK pathways are involved in cell growth, differentiation, and survival. They involve a receptor with tyrosine kinase activity that phosphorylates other proteins upon ligand binding. This phosphorylation event triggers a signaling cascade that ultimately leads to the activation of transcription factors, which regulate gene expression.

Ion channel-linked pathways involve ion channels that open or close in response to ligand binding. This change in ion permeability can lead to changes in membrane potential or intracellular calcium levels, triggering downstream signaling events.

The final step in signal transduction is the cellular response. The signal transmitted through the signaling pathway ultimately leads to a specific cellular response, such as changes in gene expression, protein synthesis, enzyme activity, or cell behavior. The cellular response can be rapid and transient, or it can be slow and long-lasting, depending on the nature of the signal and the signaling pathway involved.

In summary, signal transduction is a highly regulated and complex process that allows cells to communicate with their environment and respond to external stimuli. It involves a series of steps that include reception, transduction, and cellular response, and it is essential for the proper functioning of all living organisms.'
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Proteins (271)

Compounds (3,302)