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.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSYFFIIQAVAAHEKNMREQAKKMNVASLRSAENQN 70
Cdd:cd15079  148 TSCSFDYLTRDWNTRSFVATIFVFAYVIPLIIIIYCYSFIVKAVFAHEKALREQAKKMNVVSLRSNADAN 217

insect photoreceptors R1-R6 and similar proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes the insect photoreceptors and their closely related proteins. The Drosophila eye is composed of about 800 unit eyes called ommatidia, each of which contains eight photoreceptor cells (R1-R8). The six outer photoreceptors (R1-R6) function like the vertebrate rods and are responsible for motion detection in dim light and image formation. The R1-R6 photoreceptors express a blue-absorbing pigment, Rhodopsin 1(Rh1). The inner photoreceptors (R7 and R8) are considered the equivalent of the color-sensitive vertebrate cone cells, which express a range of different pigments. The R7 photoreceptors express one of two different UV absorbing pigments, either Rh3 or Rh4. Likewise, the R8 photoreceptors express either the blue absorbing pigment Rh5 or green absorbing pigment Rh6. These photoreceptors belong the class A of the G protein-coupled receptors and possess seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSYFFIIQAVAAHEKNMREQAKKMNVASLRSAENQN 70
Cdd:cd15079  148 TSCSFDYLTRDWNTRSFVATIFVFAYVIPLIIIIYCYSFIVKAVFAHEKALREQAKKMNVVSLRSNADAN 217

insect photoreceptors R1-R6 and similar proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes the insect photoreceptors and their closely related proteins. The Drosophila eye is composed of about 800 unit eyes called ommatidia, each of which contains eight photoreceptor cells (R1-R8). The six outer photoreceptors (R1-R6) function like the vertebrate rods and are responsible for motion detection in dim light and image formation. The R1-R6 photoreceptors express a blue-absorbing pigment, Rhodopsin 1(Rh1). The inner photoreceptors (R7 and R8) are considered the equivalent of the color-sensitive vertebrate cone cells, which express a range of different pigments. The R7 photoreceptors express one of two different UV absorbing pigments, either Rh3 or Rh4. Likewise, the R8 photoreceptors express either the blue absorbing pigment Rh5 or green absorbing pigment Rh6. These photoreceptors belong the class A of the G protein-coupled receptors and possess seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSYFFIIQAVAAHEKNMREQAKKMNVASLRSAENQN 70
Cdd:cd15079  148 TSCSFDYLTRDWNTRSFVATIFVFAYVIPLIIIIYCYSFIVKAVFAHEKALREQAKKMNVVSLRSNADAN 217

invertebrate Gq opsins, member of the class A family of seven-transmembrane G protein-coupled receptors; The invertebrate Gq-coupled opsin subfamily includes the arthropod and mollusc visual opsins. Like the vertebrate visual opsins, arthropods possess color vision by the use of multiple opsins sensitive to different light wavelengths. The invertebrate Gq opsins are closely related to the vertebrate melanopsins, the primary photoreceptor molecules for non-visual responses to light, and the R1-R6 photoreceptors, which are the fly equivalent to the vertebrate rods. The Gq opsins belong the class A of the G protein-coupled receptors and possess seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSYFFIIQAVAAHEKNMREQAKKMNVASLRSAEN 68
Cdd:cd15337  150 TSCTFDYLSRDLNNRLFILGLFIFGFLCPLLIIIFCYVNIIRAVRNHEKEMTQTAKSGMGKDTEKNDA 217

vertebrate melanopsins (Opsin-4), member of the class A family of seven-transmembrane G protein-coupled receptors; Melanopsin (also called Opsin-4) is the G protein-coupled photopigment that mediates non-visual responses to light. In mammals, these photoresponses include the photo-entrainment of circadian rhythm, pupillary constriction, and acute nocturnal melatonin suppression. Mammalian melanopsins are expressed only in the inner retina, whereas non-mammalian vertebrate melanopsins are localized in various extra-retinal tissues such as iris, brain, pineal gland, and skin. Melanopsins belong the class A of the G protein-coupled receptors and possess seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSYFFIIQAVAAHEKNMREQAKKMN 59
Cdd:cd15336  149 TSCTWDYMTFTPSVRAYTMLLFCFVFFIPLGIIIYCYLFIFLAIRSTGREVQKLGSQDR 207

neuropsin (Opsin-5), member of the class A family of seven-transmembrane G protein-coupled receptors; Neuropsin, also known as Opsin-5, is a photoreceptor protein expressed in the retina, brain, testes, and spinal cord. Neuropsin belongs to the type 2 opsin family of the class A G-protein coupled receptors. Mammalian neuropsin activates Gi protein-mediated photo-transduction pathway in a UV-dependent manner, whereas, in non-mammalian vertebrates, neuropsin is involved in regulating the photoperiodic control of seasonal reproduction in birds such as quail. As with other opsins, it may also act as a retinal photoisomerase.

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gi 859812185   1 TAC-----GTDYLTKDMlsrSYILVYSIFVYFLPLFLIIYSYFFIIQAVAAHEK 49
Cdd:cd15074  148 TSCsidwtGASASVGGM---SYIISIFIFCYLLPVLIIVFSYVKIIRKVKSSRK 198

non-visual pinopsins, member of the class A family of seven-transmembrane G protein-coupled receptors; Pinopsins are found in the pineal organ of birds, reptiles and amphibians, but are absent from teleosts and mammals. The vertebrate non-visual opsin family includes pinopsins, parapinopsin, VA (vertebrate ancient) opsins, and parietopsins. These non-visual opsins are expressed in various extra-retinal tissues and/or in non-rod, non-cone retinal cells. They are thought to be involved in light-dependent physiological functions such as photo-entrainment of circadian rhythm, photoperiodicity and body color change. Pinopsins belong the class A of the G protein-coupled receptors and possess seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSY---FFIIQAVAAHEK 49
Cdd:cd15084  158 TSCGPNWYTGGTNNNSYILALFVTCFALPLSTIIFSYsnlLLTLRAVAAQQK 209

olfactory receptor subfamily 10A and related proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes human olfactory receptor 10A, 10C, 10H, 10J, 10V, 10R, 10J, 10W, among others, and related proteins in other mammals, sauropsids, and amphibians. Olfactory receptors (ORs) play a central role in olfaction, the sense of smell. ORs belong to the class A rhodopsin-like family of G protein-coupled receptors and constitute the largest multigene family in mammals of approximately 1,000 genes. More than 60% of human ORs are non-functional pseudogenes compared to only 20% in mouse. Each OR can recognize structurally similar odorants, and a single odorant can be detected by several ORs. Binding of an odorant to the olfactory receptor induces a conformational change that leads to the activation of the olfactory-specific G protein (Golf). The G protein (Golf and/or Gs) in turn stimulates adenylate cyclase to make cAMP. The cAMP opens cyclic nucleotide-gated ion channels, which allow the influx of calcium and sodium ions, resulting in depolarization of the olfactory receptor neuron and triggering an action potential which transmits this information to the brain. A consensus nomenclature system based on evolutionary divergence is used here to classify the olfactory receptor family. The nomenclature begins with the root name OR, followed by an integer representing a family, a letter denoting a subfamily, and an integer representing the individual gene within the subfamily.

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gi 859812185  18 ILVYSIFVYFLPLFLIIYSYFFIIQAV 44
Cdd:cd15225  175 IFVASVLVILVPFLLILVSYIFIISTI 201

non-visual parapinopsin, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes the non-visual pineal pigment, parapinopsin, which is a member of the class A of the seven transmembrane G protein-coupled receptors. Parapinopsin serves as a UV-sensitive pigment for the wavelength discrimination in the pineal-related organs of lower vertebrates such as reptiles, amphibians, and fish. Although parapinopsin is phylogenetically related to vertebrate visual pigments such as rhodopsin, which releases its retinal chromophore and bleaches, the parapinopsin photoproduct is stable and does not bleach. The vertebrate non-visual opsin family includes pinopsins, parapinopsin, VA (vertebrate ancient) opsins, and parietopsins. These non-visual opsins are expressed in various extra-retinal tissues and/or in non-rod, non-cone retinal cells.

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gi 859812185   1 TACGTDYLTKDMLSRSYILVYSIFVYFLPLFLIIYSY 37
Cdd:cd15075  148 TSCAPDWYSRDPVNVSYILCYFSFCFAIPFAIILVSY 184

long wave-sensitive opsins, member of the class A family of seven-transmembrane G protein-coupled receptors; Long Wave-Sensitive opsin is also called red-sensitive opsin or red cone photoreceptor pigment, which mediates visual transduction in response to light at long wavelengths. Vertebrate cone opsins are expressed in cone photoreceptor cells of the retina and involved in mediating photopic vision, which allows color perception. The cone opsins can be classified into four classes according to their peak absorption wavelengths: SWS1 (ultraviolet sensitive), SWS2 (short wave-sensitive), MWS/LWS (medium/long wave-sensitive), and RH2 (medium wave-sensitive, rhodopsin-like opsins). Members of this group belong to the class A of the G protein-coupled receptors and possess seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops.

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gi 859812185   1 TACGTDYLT--KDMLSRSYILVYSIFVYFLPLFLIIYSY---FFIIQAVAAHEKNMREQAK 56
Cdd:cd15081  160 TSCGPDVFSgsSDPGVQSYMIVLMITCCIIPLAIIILCYlqvWLAIRAVAQQQKESESTQK 220