Team:Queens Canada/Project/Intro
From 2011.igem.org
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<regulartext>G-protein Coupled receptors are seven-transmembrane domain receptors (also known as serpentine, 7TM, or G-protein-linked receptors) that bind ligands extracellularly, resulting in the activation of a signal transduction pathway within the cell upon ligand binding. They are sensory receptors which may bind lipids, peptides, light sensitive molecules, odour molecules, pheromones, hormones, ions, or neurotransmitters. GPCRs exist only in eukaryotic organisms where they affect many physiological processes including the visual and olefactory senses, behavioural and immune system regulation, autonomic nervous system transmission, and cell density sensing. </regulartext><p> | <regulartext>G-protein Coupled receptors are seven-transmembrane domain receptors (also known as serpentine, 7TM, or G-protein-linked receptors) that bind ligands extracellularly, resulting in the activation of a signal transduction pathway within the cell upon ligand binding. They are sensory receptors which may bind lipids, peptides, light sensitive molecules, odour molecules, pheromones, hormones, ions, or neurotransmitters. GPCRs exist only in eukaryotic organisms where they affect many physiological processes including the visual and olefactory senses, behavioural and immune system regulation, autonomic nervous system transmission, and cell density sensing. </regulartext><p> | ||
- | <regulartext>These receptors are integral membrane proteins with helical domains that span through the cell membrane. While the extracellular domain is available to bind an agonist or antagonist (ligand), the intracellular domain is coupled to a Guanine Nucleotide Binding Protein (G-Protein). The G-protein acts as a molecular switch, where the binding of GTP (guanosine triphosphate) represents the switch being “on” and the binding of GDP represents the switch being “off”. | + | <regulartext>These receptors are integral membrane proteins with helical domains that span through the cell membrane. While the extracellular domain is available to bind an agonist or antagonist (ligand), the intracellular domain is coupled to a Guanine Nucleotide Binding Protein (G-Protein). The G-protein acts as a molecular switch, where the binding of GTP (guanosine triphosphate) represents the switch being “on” and the binding of GDP represents the switch being “off”.</regulartext><p> |
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+ | <regulartext>The consequences of the switch being “on” or “off” relates to what occurs within the cell. The family of G-proteins which bind to GPCRs are termed Heterotrimeric G-proteins and are comprised of alpha, beta, and gamma subunits. In response to a conformational change in the GPCR, which results after a ligand binds to the GPCR, the G-protein exchanges a GDP for a GTP and then dissociates from the cell membrane to initiate a signal cascade within the cell, resulting in a biological response.</regulartext><p> | ||
<regulartext>A GPCR is activated when a ligand binds to its extracellular domain. This activation induces a conformational change in the receptor and allows it to act as a guanine nucleotide exchange factor (GEF) which trades GDP for GTP on the Gα subunit of the G-protein. The Gα subunit may then dissociate from the Gβγ dimer, which anchors the G-protein to the membrane, and the GPCR to affect intracellular signalling proteins or target functional proteins directly depending on the α subunit type. Once dissociated, a new Gα subunit with bound GTP binds to the Gβγ subunit, and hence, signalling via GPCR may continue. The process is seen in the figure below.</regulartext> | <regulartext>A GPCR is activated when a ligand binds to its extracellular domain. This activation induces a conformational change in the receptor and allows it to act as a guanine nucleotide exchange factor (GEF) which trades GDP for GTP on the Gα subunit of the G-protein. The Gα subunit may then dissociate from the Gβγ dimer, which anchors the G-protein to the membrane, and the GPCR to affect intracellular signalling proteins or target functional proteins directly depending on the α subunit type. Once dissociated, a new Gα subunit with bound GTP binds to the Gβγ subunit, and hence, signalling via GPCR may continue. The process is seen in the figure below.</regulartext> |
Revision as of 23:29, 22 October 2011