probable G-protein coupled receptor 156 isoform X2 [Mus musculus]
Protein Classification
G protein-coupled receptor family protein( domain architecture ID 705710)
G protein-coupled receptor family protein is a seven-transmembrane G protein-coupled receptor (7TM-GPCR) family protein which typically transmits an extracellular signal into the cell by the conformational rearrangement of the 7TM helices and by the subsequent binding and activation of an intracellular heterotrimeric G protein; GPCR ligands include light-sensitive compounds, odors, pheromones, hormones, and neurotransmitters
List of domain hits
| Name | Accession | Description | Interval | E-value | |||||
| 7tm_GPCRs super family | cl28897 | seven-transmembrane G protein-coupled receptor superfamily; This hierarchical evolutionary ... |
48-315 | 3.92e-138 | |||||
seven-transmembrane G protein-coupled receptor superfamily; This hierarchical evolutionary model represents the seven-transmembrane (7TM) receptors, often referred to as G protein-coupled receptors (GPCRs), which transmit physiological signals from the outside of the cell to the inside via G proteins. GPCRs constitute the largest known superfamily of transmembrane receptors across the three kingdoms of life that respond to a wide variety of extracellular stimuli including peptides, lipids, neurotransmitters, amino acids, hormones, and sensory stimuli such as light, smell and taste. All GPCRs share a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes. However, some 7TM receptors, such as the type 1 microbial rhodopsins, do not activate G proteins. Based on sequence similarity, GPCRs can be divided into six major classes: class A (the rhodopsin-like family), class B (the Methuselah-like, adhesion and secretin-like receptor family), class C (the metabotropic glutamate receptor family), class D (the fungal mating pheromone receptors), class E (the cAMP receptor family), and class F (the frizzled/smoothened receptor family). Nearly 800 human GPCR genes have been identified and are involved essentially in all major physiological processes. Approximately 40% of clinically marketed drugs mediate their effects through modulation of GPCR function for the treatment of a variety of human diseases including bacterial infections. The actual alignment was detected with superfamily member cd15292: Pssm-ID: 475119 Cd Length: 268 Bit Score: 394.11 E-value: 3.92e-138
|
|||||||||
| Name | Accession | Description | Interval | E-value | |||||
| 7tmC_GPR156 | cd15292 | orphan GPR156, member of the class C family of seven-transmembrane G protein-coupled receptors; ... |
48-315 | 3.92e-138 | |||||
orphan GPR156, member of the class C family of seven-transmembrane G protein-coupled receptors; This subgroup represents orphan GPR156 that is closely related to the type B receptor for gamma-aminobutyric acid (GABA-B), which is activated by its endogenous ligand GABA, the principal inhibitory neurotransmitter. The functional GABA-B receptor is an obligatory heterodimer composed of two related subunits, GABA-B1, which is primarily involved in GABA ligand binding, and GABA-B2, which is responsible for both G-protein coupling and trafficking of the heterodimer to the plasma membrane. Activation of GABA-B couples to G(i/o)-type G proteins, which in turn modulate three major downstream effectors: adenylate cyclase, voltage-sensitive Ca2+ channels, and inwardly-rectifying K+ channels. Consequently, GABA-B receptor produces slow and sustained inhibitory responses by decreased neurotransmitter release via inhibition of Ca2+ channels and by postsynaptic hyperpolarization via the activation of K+ channels through the G-protein beta-gamma dimer. The GABA-B is expressed in both pre- and postsynaptic sites of glutamatergic and GABAergic neurons in the brain where it regulates synaptic activity. Thus, the GABA-B receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in multiple sclerosis patients. Moreover, GABA-B antagonists improves cognitive performance in mammals, while GABA-B agonists suppress cognitive behavior. In most of the class C family members, the extracellular Venus-flytrap domain in the N-terminus is connected to the seven-transmembrane (7TM) via a cysteine-rich domain (CRD). However, in the GABA-B receptor, the CRD is absent in both subunits and the Venus-flytrap ligand-binding domain is directly connected to the 7TM via a 10-15 amino acids linker, suggesting that GABA-B receptor may utilize a different activation mechanism. Pssm-ID: 320419 Cd Length: 268 Bit Score: 394.11 E-value: 3.92e-138
|
|||||||||
| 7tm_3 | pfam00003 | 7 transmembrane sweet-taste receptor of 3 GCPR; This is a domain of seven transmembrane ... |
45-310 | 1.55e-21 | |||||
7 transmembrane sweet-taste receptor of 3 GCPR; This is a domain of seven transmembrane regions that forms the C-terminus of some subclass 3 G-coupled-protein receptors. It is often associated with a downstream cysteine-rich linker domain, NCD3G pfam07562, which is the human sweet-taste receptor, and the N-terminal domain, ANF_receptor pfam01094. The seven TM regions assemble in such a way as to produce a docking pocket into which such molecules as cyclamate and lactisole have been found to bind and consequently confer the taste of sweetness. Pssm-ID: 459626 [Multi-domain] Cd Length: 247 Bit Score: 92.34 E-value: 1.55e-21
|
|||||||||
| Name | Accession | Description | Interval | E-value | |||||
| 7tmC_GPR156 | cd15292 | orphan GPR156, member of the class C family of seven-transmembrane G protein-coupled receptors; ... |
48-315 | 3.92e-138 | |||||
orphan GPR156, member of the class C family of seven-transmembrane G protein-coupled receptors; This subgroup represents orphan GPR156 that is closely related to the type B receptor for gamma-aminobutyric acid (GABA-B), which is activated by its endogenous ligand GABA, the principal inhibitory neurotransmitter. The functional GABA-B receptor is an obligatory heterodimer composed of two related subunits, GABA-B1, which is primarily involved in GABA ligand binding, and GABA-B2, which is responsible for both G-protein coupling and trafficking of the heterodimer to the plasma membrane. Activation of GABA-B couples to G(i/o)-type G proteins, which in turn modulate three major downstream effectors: adenylate cyclase, voltage-sensitive Ca2+ channels, and inwardly-rectifying K+ channels. Consequently, GABA-B receptor produces slow and sustained inhibitory responses by decreased neurotransmitter release via inhibition of Ca2+ channels and by postsynaptic hyperpolarization via the activation of K+ channels through the G-protein beta-gamma dimer. The GABA-B is expressed in both pre- and postsynaptic sites of glutamatergic and GABAergic neurons in the brain where it regulates synaptic activity. Thus, the GABA-B receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in multiple sclerosis patients. Moreover, GABA-B antagonists improves cognitive performance in mammals, while GABA-B agonists suppress cognitive behavior. In most of the class C family members, the extracellular Venus-flytrap domain in the N-terminus is connected to the seven-transmembrane (7TM) via a cysteine-rich domain (CRD). However, in the GABA-B receptor, the CRD is absent in both subunits and the Venus-flytrap ligand-binding domain is directly connected to the 7TM via a 10-15 amino acids linker, suggesting that GABA-B receptor may utilize a different activation mechanism. Pssm-ID: 320419 Cd Length: 268 Bit Score: 394.11 E-value: 3.92e-138
|
|||||||||
| 7tmC_GABA-B-like | cd15047 | gamma-aminobutyric acid type B receptor and related proteins, member of the class C family of ... |
48-316 | 2.92e-50 | |||||
gamma-aminobutyric acid type B receptor and related proteins, member of the class C family of seven-transmembrane G protein-coupled receptors; The type B receptor for gamma-aminobutyric acid, GABA-B, is activated by its endogenous ligand GABA, the principal inhibitory neurotransmitter. The functional GABA-B receptor is an obligatory heterodimer composed of two related subunits, GABA-B1, which is primarily involved in GABA ligand binding, and GABA-B2, which is responsible for both G-protein coupling and trafficking of the heterodimer to the plasma membrane. Activation of GABA-B couples to G(i/o)-type G proteins, which in turn modulate three major downstream effectors: adenylate cyclase, voltage-sensitive Ca2+ channels, and inwardly-rectifying K+ channels. Consequently, GABA-B receptor produces slow and sustained inhibitory responses by decreased neurotransmitter release via inhibition of Ca2+ channels and by postsynaptic hyperpolarization via the activation of K+ channels through the G-protein beta-gamma dimer. The GABA-B is expressed in both pre- and postsynaptic sites of glutamatergic and GABAergic neurons in the brain where it regulates synaptic activity. Thus, the GABA-B receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in multiple sclerosis patients. Moreover, GABA-B antagonists improves cognitive performance in mammals, while GABA-B agonists suppress cognitive behavior. In most of the class C family members, the extracellular Venus-flytrap domain in the N-terminus is connected to the seven-transmembrane (7TM) via a cysteine-rich domain (CRD). However, in the GABA-B receptor, the CRD is absent in both subunits and the Venus-flytrap ligand-binding domain is directly connected to the 7TM via a 10-15 amino acids linker, suggesting that GABA-B receptor may utilize a different activation mechanism. Also included in this group are orphan receptors, GPR156 and GPR158, which are closely related to the GABA-B receptor family. Pssm-ID: 320175 Cd Length: 263 Bit Score: 169.28 E-value: 2.92e-50
|
|||||||||
| 7tmC_GABA-B-R2 | cd15294 | gamma-aminobutyric acid type B receptor subunit 2, member of the class C family of ... |
52-312 | 3.29e-31 | |||||
gamma-aminobutyric acid type B receptor subunit 2, member of the class C family of seven-transmembrane G protein-coupled receptors; The type B receptor for gamma-aminobutyric acid, GABA-B, is activated by its endogenous ligand GABA, the principal inhibitory neurotransmitter. The functional GABA-B receptor is an obligatory heterodimer composed of two related subunits, GABA-B1, which is primarily involved in GABA ligand binding, and GABA-B2, which is responsible for both G-protein coupling and trafficking of the heterodimer to the plasma membrane. Activation of GABA-B couples to G(i/o)-type G proteins, which in turn modulate three major downstream effectors: adenylate cyclase, voltage-sensitive Ca2+ channels, and inwardly-rectifying K+ channels. Consequently, GABA-B receptor produces slow and sustained inhibitory responses by decreased neurotransmitter release via inhibition of Ca2+ channels and by postsynaptic hyperpolarization via the activation of K+ channels through the G-protein beta-gamma dimer. The GABA-B is expressed in both pre- and postsynaptic sites of glutamatergic and GABAergic neurons in the brain where it regulates synaptic activity. Thus, the GABA-B receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in multiple sclerosis patients. Moreover, GABA-B antagonists improves cognitive performance in mammals, while GABA-B agonists suppress cognitive behavior. In most of the class C family members, the extracellular Venus-flytrap domain in the N-terminus is connected to the seven-transmembrane (7TM) via a cysteine-rich domain (CRD). However, in the GABA-B receptor, the CRD is absent in both subunits and the Venus-flytrap ligand-binding domain is directly connected to the 7TM via a 10-15 amino acids linker, suggesting that GABA-B receptor may utilize a different activation mechanism. Pssm-ID: 320421 Cd Length: 270 Bit Score: 119.45 E-value: 3.29e-31
|
|||||||||
| 7tm_3 | pfam00003 | 7 transmembrane sweet-taste receptor of 3 GCPR; This is a domain of seven transmembrane ... |
45-310 | 1.55e-21 | |||||
7 transmembrane sweet-taste receptor of 3 GCPR; This is a domain of seven transmembrane regions that forms the C-terminus of some subclass 3 G-coupled-protein receptors. It is often associated with a downstream cysteine-rich linker domain, NCD3G pfam07562, which is the human sweet-taste receptor, and the N-terminal domain, ANF_receptor pfam01094. The seven TM regions assemble in such a way as to produce a docking pocket into which such molecules as cyclamate and lactisole have been found to bind and consequently confer the taste of sweetness. Pssm-ID: 459626 [Multi-domain] Cd Length: 247 Bit Score: 92.34 E-value: 1.55e-21
|
|||||||||
| 7tmC_GABA-B-R1 | cd15291 | gamma-aminobutyric acid type B receptor subunit 1, member of the class C family of ... |
53-237 | 1.74e-16 | |||||
gamma-aminobutyric acid type B receptor subunit 1, member of the class C family of seven-transmembrane G protein-coupled receptors; The type B receptor for gamma-aminobutyric acid, GABA-B, is activated by its endogenous ligand GABA, the principal inhibitory neurotransmitter. The functional GABA-B receptor is an obligatory heterodimer composed of two related subunits, GABA-B1, which is primarily involved in GABA ligand binding, and GABA-B2, which is responsible for both G-protein coupling and trafficking of the heterodimer to the plasma membrane. Activation of GABA-B couples to G(i/o)-type G proteins, which in turn modulate three major downstream effectors: adenylate cyclase, voltage-sensitive Ca2+ channels, and inwardly-rectifying K+ channels. Consequently, GABA-B receptor produces slow and sustained inhibitory responses by decreased neurotransmitter release via inhibition of Ca2+ channels and by postsynaptic hyperpolarization via the activation of K+ channels through the G-protein beta-gamma dimer. The GABA-B is expressed in both pre- and postsynaptic sites of glutamatergic and GABAergic neurons in the brain where it regulates synaptic activity. Thus, the GABA-B receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in multiple sclerosis patients. Moreover, GABA-B antagonists improves cognitive performance in mammals, while GABA-B agonists suppress cognitive behavior. In most of the class C family members, the extracellular Venus-flytrap domain in the N-terminus is connected to the seven-transmembrane (7TM) via a cysteine-rich domain (CRD). However, in the GABA-B receptor, the CRD is absent in both subunits and the Venus-flytrap ligand-binding domain is directly connected to the 7TM via a 10-15 amino acids linker, suggesting that GABA-B receptor may utilize a different activation mechanism. Pssm-ID: 320418 Cd Length: 274 Bit Score: 78.53 E-value: 1.74e-16
|
|||||||||
| 7tm_classC_mGluR-like | cd13953 | metabotropic glutamate receptor-like class C family of seven-transmembrane G protein-coupled ... |
72-189 | 3.35e-09 | |||||
metabotropic glutamate receptor-like class C family of seven-transmembrane G protein-coupled receptors superfamily; The class C GPCRs consist of glutamate receptors (mGluR1-8), the extracellular calcium-sensing receptors (caSR), the gamma-amino-butyric acid type B receptors (GABA-B), the vomeronasal type-2 pheromone receptors (V2R), the type 1 taste receptors (TAS1R), and the promiscuous L-alpha-amino acid receptor (GPRC6A), as well as several orphan receptors. Structurally, these receptors are typically composed of a large extracellular domain containing a Venus flytrap module which possesses the orthosteric agonist-binding site, a cysteine-rich domain (CRD) with the exception of GABA-B receptors, and the seven-transmembrane domains responsible for G protein activation. Moreover, the Venus flytrap module shows high structural homology with bacterial periplasmic amino acid-binding proteins, which serve as primary receptors in transport of a variety of soluble substrates such as amino acids and polysaccharides, among many others. The class C GPCRs exist as either homo- or heterodimers, which are essential for their function. The GABA-B1 and GABA-B2 receptors form a heterodimer via interactions between the N-terminal Venus flytrap modules and the C-terminal coiled-coiled domains. On the other hand, heterodimeric CaSRs and Tas1Rs and homodimeric mGluRs utilize Venus flytrap interactions and intermolecular disulphide bonds between cysteine residues located in the cysteine-rich domain (CRD), which can also acts as a molecular link to mediate the signal between the Venus flytrap and the 7TMs. Furthermore, members of the class C GPCRs bind a variety of endogenous ligands, ranging from amino acids, ions, to pheromones and sugar molecules, and play important roles in many physiological processes such as synaptic transmission, calcium homeostasis, and the sensation of sweet and umami tastes. Pssm-ID: 320091 [Multi-domain] Cd Length: 251 Bit Score: 56.86 E-value: 3.35e-09
|
|||||||||
| 7tmC_GPR158-like | cd15293 | orphan GPR158 and similar proteins, member of the class C family of seven-transmembrane G ... |
71-188 | 1.04e-07 | |||||
orphan GPR158 and similar proteins, member of the class C family of seven-transmembrane G protein-coupled receptors; This group includes orphan receptors GPR158, GPR158-like (also called GPR179) and similar proteins. These orphan receptors are closely related to the type B receptor for gamma-aminobutyric acid (GABA-B), which is activated by its endogenous ligand GABA, the principal inhibitory neurotransmitter. The functional GABA-B receptor is an obligatory heterodimer composed of two related subunits, GABA-B1, which is primarily involved in GABA ligand binding, and GABA-B2, which is responsible for both G-protein coupling and trafficking of the heterodimer to the plasma membrane. Activation of GABA-B couples to G(i/o)-type G proteins, which in turn modulate three major downstream effectors: adenylate cyclase, voltage-sensitive Ca2+ channels, and inwardly-rectifying K+ channels. Consequently, GABA-B receptor produces slow and sustained inhibitory responses by decreased neurotransmitter release via inhibition of Ca2+ channels and by postsynaptic hyperpolarization via the activation of K+ channels through the G-protein beta-gamma dimer. The GABA-B is expressed in both pre- and postsynaptic sites of glutamatergic and GABAergic neurons in the brain where it regulates synaptic activity. Thus, the GABA-B receptor agonist, baclofen, is used to treat muscle tightness and cramping caused by spasticity in multiple sclerosis patients. Moreover, GABA-B antagonists improves cognitive performance in mammals, while GABA-B agonists suppress cognitive behavior. In most of the class C family members, the extracellular Venus-flytrap domain in the N-terminus is connected to the seven-transmembrane (7TM) via a cysteine-rich domain (CRD). However, in the GABA-B receptor, the CRD is absent in both subunits and the Venus-flytrap ligand-binding domain is directly connected to the 7TM via a 10-15 amino acids linker, suggesting that GABA-B receptor may utilize a different activation mechanism. Pssm-ID: 320420 Cd Length: 252 Bit Score: 52.60 E-value: 1.04e-07
|
|||||||||
| 7tmC_mGluR4 | cd15452 | metabotropic glutamate receptor 4 in group 3, member of the class C family of ... |
41-192 | 1.62e-04 | |||||
metabotropic glutamate receptor 4 in group 3, member of the class C family of seven-transmembrane G protein-coupled receptors; The receptors in group 3 include mGluRs 4, 6, 7, and 8. They are homodimeric class C G-protein coupled receptors which are activated by glutamate, the major excitatory neurotransmitter of the CNS. mGluRs are involved in regulating neuronal excitability and synaptic transmission via intracellular activation of second messenger signaling pathways. While the ionotropic glutamate receptor subtypes (AMPA, NMDA, and kainite) mediate fast excitatory postsynaptic transmission, mGluRs are known to mediate slower excitatory postsynaptic responses and to be involved in synaptic plasticity in the mammalian brain. In addition to seven-transmembrane helices, the class C GPCRs are characterized by a large N-terminal extracellular Venus flytrap-like domain, which is composed of two adjacent lobes separated by a cleft which binds an endogenous ligand. Moreover, they exist as either homo- or heterodimers, which are essential for their function. For instance, mGluRs form homodimers via interactions between the N-terminal Venus flytrap domains and the intermolecular disulphide bonds between cysteine residues located in the cysteine-rich domain (CRD). At least eight different subtypes of metabotropic receptors (mGluR1-8) have been identified and further classified into three groups based on their sequence homology, pharmacological properties, and signaling pathways. Group 1 (mGluR1 and mGluR5) receptors are predominantly located postsynaptically on neurons and are involved in long-term synaptic plasticity in the brain, including long-term potentiation (LTP) in the hippocampus and long-term depression (LTD) in the cerebellum. They are coupled to G(q/11) proteins, thereby activating phospholipase C to generate inositol-1,4,5-triphosphate (IP3) and diacyglycerol (DAG), which in turn lead to Ca2+ release and protein kinase C activation, respectively. Group 1 mGluR expression is shown to be strongly upregulated in animal models of epilepsy, brain injury, inflammatory, and neuropathic pain, as well as in patients with amyotrophic lateral sclerosis or multiple sclerosis. Group 2 (mGluR2 and mGluR3) and 3 (mGluR4, mGluR6, mGluR7, and mGluR8) receptors are predominantly localized presynaptically in the active region of neurotransmitter release. They are coupled to G(i/o) proteins, which leads to inhibition of adenylate cyclase activity and cAMP formation, and consequently to a decrease in protein kinase A (PKA) activity. Ultimately, activation of these receptors leads to inhibition of neurotransmitter release such as glutamate and GABA via inhibition of Ca2+ channels and activation of K+ channels. Furthermore, while activation of Group 1 mGluRs increases NMDA (N-methyl-D-aspartate) receptor activity and risk of neurotoxicity, Group 2 and 3 mGluRs decrease NMDA receptor activity and prevent neurotoxicity. Pssm-ID: 320568 [Multi-domain] Cd Length: 327 Bit Score: 43.05 E-value: 1.62e-04
|
|||||||||
| 7tmC_mGluR_group3 | cd15286 | metabotropic glutamate receptors in group 3, member of the class C family of ... |
41-192 | 3.12e-04 | |||||
metabotropic glutamate receptors in group 3, member of the class C family of seven-transmembrane G protein-coupled receptors; The metabotropic glutamate receptors (mGluRs) in group 3 include mGluRs 4, 6, 7, and 8. They are homodimeric class C G-protein coupled receptors which are activated by glutamate, the major excitatory neurotransmitter of the CNS. mGluRs are involved in regulating neuronal excitability and synaptic transmission via intracellular activation of second messenger signaling pathways. While the ionotropic glutamate receptor subtypes (AMPA, NMDA, and kainite) mediate fast excitatory postsynaptic transmission, mGluRs are known to mediate slower excitatory postsynaptic responses and to be involved in synaptic plasticity in the mammalian brain. In addition to seven-transmembrane helices, the class C GPCRs are characterized by a large N-terminal extracellular Venus flytrap-like domain, which is composed of two adjacent lobes separated by a cleft which binds an endogenous ligand. Moreover, they exist as either homo- or heterodimers, which are essential for their function. For instance, mGluRs form homodimers via interactions between the N-terminal Venus flytrap domains and the intermolecular disulphide bonds between cysteine residues located in the cysteine-rich domain (CRD). At least eight different subtypes of metabotropic receptors (mGluR1-8) have been identified and further classified into three groups based on their sequence homology, pharmacological properties, and signaling pathways. Group 1 (mGluR1 and mGluR5) receptors are predominantly located postsynaptically on neurons and are involved in long-term synaptic plasticity in the brain, including long-term potentiation (LTP) in the hippocampus and long-term depression (LTD) in the cerebellum. They are coupled to G(q/11) proteins, thereby activating phospholipase C to generate inositol-1,4,5-triphosphate (IP3) and diacyglycerol (DAG), which in turn lead to Ca2+ release and protein kinase C activation, respectively. Group 1 mGluR expression is shown to be strongly upregulated in animal models of epilepsy, brain injury, inflammatory, and neuropathic pain, as well as in patients with amyotrophic lateral sclerosis or multiple sclerosis. Group 2 (mGluR2 and mGluR3) and 3 (mGluR4, mGluR6, mGluR7, and mGluR8) receptors are predominantly localized presynaptically in the active region of neurotransmitter release. They are coupled to G(i/o) proteins, which leads to inhibition of adenylate cyclase activity and cAMP formation, and consequently to a decrease in protein kinase A (PKA) activity. Ultimately, activation of these receptors leads to inhibition of neurotransmitter release such as glutamate and GABA via inhibition of Ca2+ channels and activation of K+ channels. Furthermore, while activation of Group 1 mGluRs increases NMDA (N-methyl-D-aspartate) receptor activity and risk of neurotoxicity, Group 2 and 3 mGluRs decrease NMDA receptor activity and prevent neurotoxicity. Pssm-ID: 320413 Cd Length: 271 Bit Score: 42.10 E-value: 3.12e-04
|
|||||||||
| 7tmC_mGluR6 | cd15453 | metabotropic glutamate receptor 6 in group 3, member of the class C family of ... |
41-188 | 5.68e-03 | |||||
metabotropic glutamate receptor 6 in group 3, member of the class C family of seven-transmembrane G protein-coupled receptors; The receptors in group 3 include mGluRs 4, 6, 7, and 8. They are homodimeric class C G-protein coupled receptors which are activated by glutamate, the major excitatory neurotransmitter of the CNS. mGluRs are involved in regulating neuronal excitability and synaptic transmission via intracellular activation of second messenger signaling pathways. While the ionotropic glutamate receptor subtypes (AMPA, NMDA, and kainite) mediate fast excitatory postsynaptic transmission, mGluRs are known to mediate slower excitatory postsynaptic responses and to be involved in synaptic plasticity in the mammalian brain. In addition to seven-transmembrane helices, the class C GPCRs are characterized by a large N-terminal extracellular Venus flytrap-like domain, which is composed of two adjacent lobes separated by a cleft which binds an endogenous ligand. Moreover, they exist as either homo- or heterodimers, which are essential for their function. For instance, mGluRs form homodimers via interactions between the N-terminal Venus flytrap domains and the intermolecular disulphide bonds between cysteine residues located in the cysteine-rich domain (CRD). At least eight different subtypes of metabotropic receptors (mGluR1-8) have been identified and further classified into three groups based on their sequence homology, pharmacological properties, and signaling pathways. Group 1 (mGluR1 and mGluR5) receptors are predominantly located postsynaptically on neurons and are involved in long-term synaptic plasticity in the brain, including long-term potentiation (LTP) in the hippocampus and long-term depression (LTD) in the cerebellum. They are coupled to G(q/11) proteins, thereby activating phospholipase C to generate inositol-1,4,5-triphosphate (IP3) and diacyglycerol (DAG), which in turn lead to Ca2+ release and protein kinase C activation, respectively. Group 1 mGluR expression is shown to be strongly upregulated in animal models of epilepsy, brain injury, inflammatory, and neuropathic pain, as well as in patients with amyotrophic lateral sclerosis or multiple sclerosis. Group 2 (mGluR2 and mGluR3) and 3 (mGluR4, mGluR6, mGluR7, and mGluR8) receptors are predominantly localized presynaptically in the active region of neurotransmitter release. They are coupled to G(i/o) proteins, which leads to inhibition of adenylate cyclase activity and cAMP formation, and consequently to a decrease in protein kinase A (PKA) activity. Ultimately, activation of these receptors leads to inhibition of neurotransmitter release such as glutamate and GABA via inhibition of Ca2+ channels and activation of K+ channels. Furthermore, while activation of Group 1 mGluRs increases NMDA (N-methyl-D-aspartate) receptor activity and risk of neurotoxicity, Group 2 and 3 mGluRs decrease NMDA receptor activity and prevent neurotoxicity. Pssm-ID: 320569 [Multi-domain] Cd Length: 273 Bit Score: 38.09 E-value: 5.68e-03
|
|||||||||
| Blast search parameters | ||||
|
