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G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. They are coupled with G proteins. They pass through the cell membrane seven times in the form of six loops of amino acid residues, which is why they are sometimes referred to as seven-transmembrane receptors. Ligands can bind either to the extracellular N-terminus and loops or to the binding site within transmembrane helices. They are all activated by agonists, although a spontaneous auto-activation of an empty receptor has also been observed.
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist.
In biochemistry and pharmacology, receptors are chemical structures, composed of protein, that receive and transduce signals that may be integrated into biological systems. These signals are typically chemical messengers which bind to a receptor and produce physiological responses such as change in the electrical activity of a cell. For example, GABA, an inhibitory neurotransmitter, inhibits electrical activity of neurons by binding to GABAA receptors. There are three main ways the action of the receptor can be classified: relay of signal, amplification, or integration. Relaying sends the signal onward, amplification increases the effect of a single ligand, and integration allows the signal to be incorporated into another biochemical pathway.
A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist. Antagonist drugs interfere in the natural operation of receptor proteins. They are sometimes called blockers; examples include alpha blockers, beta blockers, and calcium channel blockers. In pharmacology, antagonists have affinity but no efficacy for their cognate receptors, and binding will disrupt the interaction and inhibit the function of an agonist or inverse agonist at receptors. Antagonists mediate their effects by binding to the active site or to the allosteric site on a receptor, or they may interact at unique binding sites not normally involved in the biological regulation of the receptor's activity. Antagonist activity may be reversible or irreversible depending on the longevity of the antagonist–receptor complex, which, in turn, depends on the nature of antagonist–receptor binding. The majority of drug antagonists achieve their potency by competing with endogenous ligands or substrates at structurally defined binding sites on receptors.
In pharmacology, an inverse agonist is a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist.
Functional selectivity is the ligand-dependent selectivity for certain signal transduction pathways relative to a reference ligand at the same receptor. Functional selectivity can be present when a receptor has several possible signal transduction pathways. To which degree each pathway is activated thus depends on which ligand binds to the receptor. Functional selectivity, or biased signaling, is most extensively characterized at G protein coupled receptors (GPCRs). A number of biased agonists, such as those at muscarinic M2 receptors tested as analgesics or antiproliferative drugs, or those at opioid receptors that mediate pain, show potential at various receptor families to increase beneficial properties while reducing side effects. For example, pre-clinical studies with G protein biased agonists at the μ-opioid receptor show equivalent efficacy for treating pain with reduced risk for addictive potential and respiratory depression. Studies within the chemokine receptor system also suggest that GPCR biased agonism is physiologically relevant. For example, a beta-arrestin biased agonist of the chemokine receptor CXCR3 induced greater chemotaxis of T cells relative to a G protein biased agonist.
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from Latin ligare, which means 'to bind'. In protein-ligand binding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein. The binding typically results in a change of conformational isomerism (conformation) of the target protein. In DNA-ligand binding studies, the ligand can be a small molecule, ion, or protein which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure.
The beta-1 adrenergic receptor, also known as ADRB1, can refer to either the protein-encoding gene or one of the four adrenergic receptors. It is a G-protein coupled receptor associated with the Gs heterotrimeric G-protein that is expressed predominantly in cardiac tissue. In addition to cardiac tissue, beta-1 adrenergic receptors are also expressed in the cerebral cortex.
The nociceptin opioid peptide receptor (NOP), also known as the nociceptin/orphanin FQ (N/OFQ) receptor or kappa-type 3 opioid receptor, is a protein that in humans is encoded by the OPRL1 gene. The nociceptin receptor is a member of the opioid subfamily of G protein-coupled receptors whose natural ligand is the 17 amino acid neuropeptide known as nociceptin (N/OFQ). This receptor is involved in the regulation of numerous brain activities, particularly instinctive and emotional behaviors. Antagonists targeting NOP are under investigation for their role as treatments for depression and Parkinson's disease, whereas NOP agonists have been shown to act as powerful, non-addictive painkillers in non-human primates.
Neuromedin N is a neuropeptide derived from the same precursor polypeptide as neurotensin, and with similar but subtly distinct expression and effects. Composed of the amino acid sequence Lys-Ile-Pro-Tyr-Ile-Leu, neuromedin N is homologous to neurotensin, both of whose sequences are found on the pro neurotensin/neuromedin N precursor C-terminus. Both sequences of neuromedin N as well as neurotensin are flanked by Lys-Arg amino acids, which comprise a consensus sequence for the endoprotease proprotein convertase. Neuromedin N is primarily synthesized in the neural and intestinal tissues of mammals; in studies performed in mice, neuromedin N's physiological effects were shown to include hypothermia and analgesia, arising from the peptide's ligand association to and interaction with neurotensin type 2 (NTS2) G protein-coupled receptors.
The MAS1 oncogene is a G protein-coupled receptor which binds the angiotensin II metabolite angiotensin (1-7). The MAS1 receptor, when activated by binding angiotensin-(1-7), opposes many of the effects of the angiotensin II receptor. Hence, MAS1 receptor agonists have similar therapeutic effects to angiotensin II receptor antagonists, including lowering of blood pressure.
Dopamine receptor D2, also known as D2R, is a protein that, in humans, is encoded by the DRD2 gene. After work from Paul Greengard's lab had suggested that dopamine receptors were the site of action of antipsychotic drugs, several groups, including those of Solomon Snyder and Philip Seeman used a radiolabeled antipsychotic drug to identify what is now known as the dopamine D2 receptor. The dopamine D2 receptor is the main receptor for most antipsychotic drugs. The structure of DRD2 in complex with the atypical antipsychotic risperidone has been determined.
Calcitonin receptor-like (CALCRL), also known as the calcitonin receptor-like receptor (CRLR), is a human protein; it is a receptor for calcitonin gene-related peptide.
Parathyroid hormone 2 receptor is a protein that in humans is encoded by the PTH2R gene.
Prostaglandin D2 receptor 2 (DP2 or CRTH2) is a human protein encoded by the PTGDR2 gene and GPR44. DP2 has also been designated as CD294 (cluster of differentiation 294). It is a member of the class of prostaglandin receptors which bind with and respond to various prostaglandins. DP2 along with Prostaglandin DP1 receptor are receptors for prostaglandin D2 (PGD2). Activation of DP2 by PGD2 or other cognate receptor ligands has been associated with certain physiological and pathological responses, particularly those associated with allergy and inflammation, in animal models and certain human diseases.
Relaxin/insulin-like family peptide receptor 4, also known as RXFP4, is a human G-protein coupled receptor.
The 5-HT7 receptor is a member of the GPCR superfamily of cell surface receptors and is activated by the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). The 5-HT7 receptor is coupled to Gs (stimulates the production of the intracellular signaling molecule cAMP) and is expressed in a variety of human tissues, particularly in the brain, the gastrointestinal tract, and in various blood vessels. This receptor has been a drug development target for the treatment of several clinical disorders. The 5-HT7 receptor is encoded by the HTR7 gene, which in humans is transcribed into 3 different splice variants.
Neurotensin receptor type 1 is a protein that in humans is encoded by the NTSR1 gene. For a crystal structure of NTS1, see pdb code 4GRV. In addition, high-resolution crystal structures have been determined in complex with the peptide full agonist NTS8-13, the non-peptide full agonist SRI-9829, the partial agonist RTI-3a, and the antagonists / inverse agonists SR48692 and SR142948A, as well as in the ligand-free apo state., see PDB codes 6YVR (NTSR1-H4X:NTS8–13), 6Z4V (NTSR1-H4bmX:NTS8–13), 6Z8N (NTSR1-H4X:SRI-9829), 6ZA8 (NTSR1-H4X:RTI-3a), 6Z4S (NTSR1-H4bmX:SR48692), 6ZIN (NTSR1-H4X:SR48692), 6Z4Q, and 6Z66.
SR-142948 is a drug used in scientific research which is a non-peptide antagonist selective for the neurotensin receptors, although not selective between subtypes.
Meclinertant (SR-48692) is a drug which acts as a selective, non-peptide antagonist at the neurotensin receptor NTS1, and was the first non-peptide antagonist developed for this receptor. It is used in scientific research to explore the interaction between neurotensin and other neurotransmitters in the brain, and produces anxiolytic, anti-addictive and memory-impairing effects in animal studies.
References
- ↑ Vincent JP, Mazella J, Kitabgi P (1999). "Neurotensin and neurotensin receptors". Trends Pharmacol. Sci. 20 (7): 302–309. doi:10.1016/S0165-6147(99)01357-7. PMID 10390649.
- ↑ Pelaprat D (2006). "Interactions between neurotensin receptors and G proteins". Peptides. 27 (10): 2476–2487. doi:10.1016/j.peptides.2006.04.027. PMID 16919370. S2CID 21730838.
- 1 2 3 Deluigi M, Klipp A, Klenk C, Merklinger L, Eberle SA, Morstein L, Heine P, Mittl PR, Ernst P, Kamenecka TM, He Y, Vacca S, Egloff P, Honegger A, Plückthun A (January 2021). "Complexes of the neurotensin receptor 1 with small-molecule ligands reveal structural determinants of full, partial, and inverse agonism". Science Advances. 7 (5): eabe5504. Bibcode:2021SciA....7.5504D. doi:10.1126/sciadv.abe5504. PMC 7840143 . PMID 33571132.
- ↑ Yamauchi R, Usui H, Yunden J, Takenaka Y, Tani F, Yoshikawa M (April 2003). "Characterization of beta-lactotensin, a bioactive peptide derived from bovine beta-lactoglobulin, as a neurotensin agonist". Bioscience, Biotechnology, and Biochemistry. 67 (4): 940–3. doi: 10.1271/bbb.67.940 . PMID 12784648. S2CID 83609327.
- ↑ Thomas JB, Navarro H, Warner KR, Gilmour B (March 2009). "The identification of nonpeptide neurotensin receptor partial agonists from the potent antagonist SR48692 using a calcium mobilization assay". Bioorganic & Medicinal Chemistry Letters. 19 (5): 1438–1441. doi:10.1016/j.bmcl.2009.01.024. PMC 4418176 . PMID 19195889.
- ↑ Bredeloux P, Costentin J, Dubuc I (December 2006). "Interactions between NTS2 neurotensin and opioid receptors on two nociceptive responses assessed on the hot plate test in mice". Behavioural Brain Research. 175 (2): 399–407. doi:10.1016/j.bbr.2006.09.016. PMID 17074405. S2CID 24790151.
- ↑ Ferraro L, Tomasini MC, Mazza R, Fuxe K, Fournier J, Tanganelli S, Antonelli T (August 2008). "Neurotensin receptors as modulators of glutamatergic transmission". Brain Research Reviews. 58 (2): 365–373. doi:10.1016/j.brainresrev.2007.11.001. PMID 18096238. S2CID 25434443.
- ↑ Attrill H, Harding PJ, Smith E, Ross S, Watts A (2009). "Improved yield of a ligand-binding GPCR expressed in E. coli for structural studies". Protein Expr Purif. 64 (1): 32–38. doi:10.1016/j.pep.2008.10.001. PMID 18976711.
- ↑ Harding PJ, Hadingham TC, McDonnell JM, Watts A (2006). "Direct analysis of a GPCR-agonist interaction by surface plasmon resonance". Eur Biophys J. 35 (8): 709–712. doi:10.1007/s00249-006-0070-x. PMID 16708210. S2CID 7844675.
- ↑ Harding PJ, Attrill H, Boehringer J, Ross S, Wadhams GH, Smith E, Armitage JP, Watts A (2009). "Constitutive dimerization of the G-protein coupled receptor, neurotensin receptor 1, reconstituted into phospholipid bilayers". Biophys. J. 96 (3): 964–973. Bibcode:2009BpJ....96..964H. doi:10.1016/j.bpj.2008.09.054. PMC 2716571 . PMID 19186134.
- ↑ Selmi DN, Adamson RJ, Attrill H, Goddard AD, Gilbert RJ, Watts A, Turberfield AJ (2011). "DNA-templated protein arrays for single-molecule imaging". Nano Lett. 11 (2): 657–660. Bibcode:2011NanoL..11..657S. doi:10.1021/nl1037769. PMID 21218848.
