Chain A, ChRmine
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 | |||||
| Bac_rhodopsin super family | cl46634 | Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide ... |
35-272 | 5.89e-21 | |||||
Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide light- dependent ion transport and sensory functions to a family of halophilic bacteria. They are integral membrane proteins believed to contain seven transmembrane (TM) domains, the last of which contains the attachment point for retinal (a conserved lysine). This family also includes distantly related proteins that do not contain the retinal binding lysine and so cannot function as opsins. Some fungal examples are: Swiss:O74870, Swiss:P25619, Swiss:P38079, Swiss:Q12117. The actual alignment was detected with superfamily member pfam01036: Pssm-ID: 460037 Cd Length: 224 Bit Score: 89.33 E-value: 5.89e-21
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| Name | Accession | Description | Interval | E-value | |||||
| Bac_rhodopsin | pfam01036 | Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide ... |
35-272 | 5.89e-21 | |||||
Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide light- dependent ion transport and sensory functions to a family of halophilic bacteria. They are integral membrane proteins believed to contain seven transmembrane (TM) domains, the last of which contains the attachment point for retinal (a conserved lysine). This family also includes distantly related proteins that do not contain the retinal binding lysine and so cannot function as opsins. Some fungal examples are: Swiss:O74870, Swiss:P25619, Swiss:P38079, Swiss:Q12117. Pssm-ID: 460037 Cd Length: 224 Bit Score: 89.33 E-value: 5.89e-21
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| COG5524 | COG5524 | Bacteriorhodopsin [Energy production and conversion, Signal transduction mechanisms]; |
34-276 | 1.06e-18 | |||||
Bacteriorhodopsin [Energy production and conversion, Signal transduction mechanisms]; Pssm-ID: 444275 Cd Length: 234 Bit Score: 83.06 E-value: 1.06e-18
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| 7tm_Opsins_type1 | cd14965 | type 1 opsins, member of the seven-transmembrane GPCR superfamily; This group represents the ... |
33-268 | 1.02e-17 | |||||
type 1 opsins, member of the seven-transmembrane GPCR superfamily; This group represents the microbial rhodopsin family, also known as type 1 rhodopsins, which can function as light-dependent ion pumps, cation channels, and sensors. They have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. Members of the type I rhodopsin family include: light-driven inward chloride pump halorhodopsin (HR); light-driven outward proton pump bacteriorhodopsin (BR); light-gated cation channel channelrhodopsin (ChR); light-sensor activating transmembrane transducer proteins, sensory rhodopsin I and II (SRI and II); light-sensor activating soluble transducer protein Anabaena sensory rhodopsin (ASR); and other light-driven proton pumps such as blue-light-absorbing and green-light absorbing proteorhodopsins, among others. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins. Pssm-ID: 410629 Cd Length: 214 Bit Score: 80.03 E-value: 1.02e-17
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| Bac_rhodopsin | smart01021 | Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide ... |
34-276 | 8.96e-15 | |||||
Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide light- dependent ion transport and sensory functions to a family of halophilic bacteria.. They are integral membrane proteins believed to contain seven transmembrane (TM) domains, the last of which contains the attachment point for retinal (a conserved lysine). Pssm-ID: 214978 Cd Length: 233 Bit Score: 72.31 E-value: 8.96e-15
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| Name | Accession | Description | Interval | E-value | |||||
| Bac_rhodopsin | pfam01036 | Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide ... |
35-272 | 5.89e-21 | |||||
Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide light- dependent ion transport and sensory functions to a family of halophilic bacteria. They are integral membrane proteins believed to contain seven transmembrane (TM) domains, the last of which contains the attachment point for retinal (a conserved lysine). This family also includes distantly related proteins that do not contain the retinal binding lysine and so cannot function as opsins. Some fungal examples are: Swiss:O74870, Swiss:P25619, Swiss:P38079, Swiss:Q12117. Pssm-ID: 460037 Cd Length: 224 Bit Score: 89.33 E-value: 5.89e-21
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| COG5524 | COG5524 | Bacteriorhodopsin [Energy production and conversion, Signal transduction mechanisms]; |
34-276 | 1.06e-18 | |||||
Bacteriorhodopsin [Energy production and conversion, Signal transduction mechanisms]; Pssm-ID: 444275 Cd Length: 234 Bit Score: 83.06 E-value: 1.06e-18
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| 7tm_Opsins_type1 | cd14965 | type 1 opsins, member of the seven-transmembrane GPCR superfamily; This group represents the ... |
33-268 | 1.02e-17 | |||||
type 1 opsins, member of the seven-transmembrane GPCR superfamily; This group represents the microbial rhodopsin family, also known as type 1 rhodopsins, which can function as light-dependent ion pumps, cation channels, and sensors. They have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. Members of the type I rhodopsin family include: light-driven inward chloride pump halorhodopsin (HR); light-driven outward proton pump bacteriorhodopsin (BR); light-gated cation channel channelrhodopsin (ChR); light-sensor activating transmembrane transducer proteins, sensory rhodopsin I and II (SRI and II); light-sensor activating soluble transducer protein Anabaena sensory rhodopsin (ASR); and other light-driven proton pumps such as blue-light-absorbing and green-light absorbing proteorhodopsins, among others. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins. Pssm-ID: 410629 Cd Length: 214 Bit Score: 80.03 E-value: 1.02e-17
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| Bac_rhodopsin | smart01021 | Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide ... |
34-276 | 8.96e-15 | |||||
Bacteriorhodopsin-like protein; The bacterial opsins are retinal-binding proteins that provide light- dependent ion transport and sensory functions to a family of halophilic bacteria.. They are integral membrane proteins believed to contain seven transmembrane (TM) domains, the last of which contains the attachment point for retinal (a conserved lysine). Pssm-ID: 214978 Cd Length: 233 Bit Score: 72.31 E-value: 8.96e-15
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| 7tm_bacteriorhodopsin | cd15244 | light-driven outward proton pump bacteriorhodopsin, member of the seven-transmembrane GPCR ... |
36-270 | 5.55e-12 | |||||
light-driven outward proton pump bacteriorhodopsin, member of the seven-transmembrane GPCR superfamily; Bacteriorhodopsin (BR) serves as a light-driven retinal-binding outward proton pump, generating an outside positive membrane potential and thus creating an inwardly directed proton motive force (PMF) necessary for ATP synthesis. BR belongs to the microbial rhodopsin family, also known as type I rhodopsins, comprising light-driven inward chloride pump halorhodopsin (HR), light-gated cation channel channelrhodopsin (ChR), light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), light-sensor activating soluble transducer protein Anabaena sensory rhodopsin (ASR), and other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. They have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320372 Cd Length: 221 Bit Score: 63.95 E-value: 5.55e-12
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| 7tm_ASR-like | cd15240 | Anabaena sensory rhodopsin and similar proteins, member of the seven-transmembrane GPCR ... |
114-264 | 9.59e-09 | |||||
Anabaena sensory rhodopsin and similar proteins, member of the seven-transmembrane GPCR superfamily; This subgroup includes eubacterial sensory rhodopsin from the freshwater cyanobacterium Anabaena and its closely related proteins. Unlike other sensory rhodopsins (SRI and SRII), the Anabaena sensory rhodopsin (ASR) activates a soluble transducer protein (ASRT), which may leading to transcriptional control of several genes. Although ASRT was shown to interact with DNA in vitro, the exact mechanism of photosensory transduction is not clearly understood. Moreover, the regulation of CRP (cAMP receptor protein) expression by ASR has been reported demonstrating a direct interaction of the C-terminal region of ASR with DNA, suggesting that ASR itself may also work as a transcription factor. ASR belongs to the microbial rhodopsin family, also known as type I rhodopsins, comprising the light-driven inward chloride pump halorhodopsin (HR), the outward proton pump bacteriorhodopsin (BR), the light-gated cation channel channelrhodopsin (ChR), the light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), and the other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. Microbial rhodopsins have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320368 Cd Length: 221 Bit Score: 54.80 E-value: 9.59e-09
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| 7tm_Opsin-1_euk | cd15028 | proton pumping rhodopsins in fungi and algae, member of the seven-transmembrane GPCR ... |
36-266 | 3.86e-05 | |||||
proton pumping rhodopsins in fungi and algae, member of the seven-transmembrane GPCR superfamily; This subgroup represents uncharacterized proton pumping rhodopsins found in fungi and algae. They belong to the microbial rhodopsin family, also known as type I rhodopsins, consisting of the light-driven inward chloride pump halorhodopsin (HR), the outward proton pump bacteriorhodopsin (BR), the light-gated cation channel channelrhodopsin (ChR), the light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), and the other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. Microbial rhodopsins have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320156 Cd Length: 231 Bit Score: 44.19 E-value: 3.86e-05
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| 7tm_SRI_SRII | cd15029 | light-sensor activating transmembrane transducer protein sensory rhodopsin I and II; member of ... |
114-269 | 2.04e-04 | |||||
light-sensor activating transmembrane transducer protein sensory rhodopsin I and II; member of the seven-transmembrane GPCR superfamily; This subgroup includes the light-sensor activating transmembrane transducer proteins, sensory rhodopsin I (SRI) and II (SRII, also called phoborhodopsin). SRI and SRII are responsible for positive (attractive) and negative (repellent) phototaxis in halobacteria, respectively, thereby controlling the cell's directional movement in response to changes in light intensity by swimming either towards or away from the light. Both sensory rhodopsins belong to the family of microbial rhodopsins, also known as type I rhodopsins, consisting of the light-driven inward chloride pump halorhodopsin (HR), the outward proton pump bacteriorhodopsin (BR), the light-gated cation channel channelrhodopsin (ChR), and the other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. Microbial rhodopsins have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320157 Cd Length: 214 Bit Score: 41.93 E-value: 2.04e-04
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| 7tm_ARII-like | cd15238 | Acetabularia rhodopsin II and similar proteins, member of the seven-transmembrane GPCR ... |
114-265 | 5.47e-04 | |||||
Acetabularia rhodopsin II and similar proteins, member of the seven-transmembrane GPCR superfamily; This subgroup includes the eukaryotic light-driven proton-pumping Acetabularia rhodopsin II from the giant unicellular marine alga Acetabularis acetabulum, as well as its closely related proteins. They belong to the microbial rhodopsin family, also known as type I rhodopsins, comprising the light-driven inward chloride pump halorhodopsin (HR), the outward proton pump bacteriorhodopsin (BR), the light-gated cation channel channelrhodopsin (ChR), the light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), and the other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. Microbial rhodopsins have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320366 Cd Length: 219 Bit Score: 40.63 E-value: 5.47e-04
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| 7tm_Halorhodopsin | cd15243 | light-driven inward chloride pump halorhodopsin, member of the seven-transmembrane GPCR ... |
170-269 | 5.58e-04 | |||||
light-driven inward chloride pump halorhodopsin, member of the seven-transmembrane GPCR superfamily; Halorhodopsin (HR) acts as a light-driven inward-directed chloride pump. When activated by yellow light, HR pumps chloride ions into the cell cytoplasm, generating a negative-inside membrane potential which drives proton uptake. The resulting electrochemical ion gradient provides an energy source to the cell and contributes to pH homeostasis. HR is found in phylogenetically ancient archaea, known as halobacteria which live in high salty environments. HR belongs to the microbial rhodopsin family, also known as type I rhodopsins, comprising light-driven retinal-binding outward pump bacteriorhodopsin (BR), light-gated cation channel channelrhodopsin (ChR), light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), light-sensor activating soluble transducer protein Anabaena sensory rhodopsin (ASR), and other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. They have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320371 Cd Length: 226 Bit Score: 40.55 E-value: 5.58e-04
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| 7tm_YRO2_fungal-like | cd15239 | fungal YRO2 and related proteins, member of the seven-transmembrane GPCR superfamily; This ... |
36-235 | 3.16e-03 | |||||
fungal YRO2 and related proteins, member of the seven-transmembrane GPCR superfamily; This subgroup includes the yeast YRO2 protein and it closely related proteins. Although the exact function of these proteins is unknown, they show strong sequence homology to the family of microbial rhodopsins, also known as type I rhodopsins, comprising the light-driven inward chloride pump halorhodopsin (HR), the outward proton pump bacteriorhodopsin (BR), the light-gated cation channel channelrhodopsin (ChR), the light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), and the other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. Microbial rhodopsins have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320367 Cd Length: 227 Bit Score: 38.26 E-value: 3.16e-03
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| 7tm_ChRs | cd15241 | channelrhodopsins, member of the seven-transmembrane GPCR superfamily; Channelrhodopsins (ChRs) ... |
212-264 | 4.66e-03 | |||||
channelrhodopsins, member of the seven-transmembrane GPCR superfamily; Channelrhodopsins (ChRs) are light-gated ion channels acting as sensory photoreceptors in unicellular green algae, controlling phototaxis (directional movement toward or away from light). ChRs are large seven-transmembrane proteins with large C-terminal extensions, which have been implicated in localizing the channel to the algal eyespot, a single layer of pigmented granules, overlaying part of the plasma membrane but are not required for ion channel function. ChRs are belongs to the microbial rhodopsin family, also known as type I rhodopsins, comprising the light-driven inward chloride pump halorhodopsin (HR), the outward proton pump bacteriorhodopsin (BR), the light-sensor activating transmembrane transducer protein sensory rhodopsin II (SRII), the light-sensor activating soluble transducer protein Anabaena sensory rhodopsin (ASR), and the other light-driven proton pumps such as blue-light absorbing and green-light absorbing proteorhodopsins, among others. Microbial rhodopsins have been found in various single-celled microorganisms from all three domains of life, including halophile archaea, gamma-proteobacteria, cyanobacteria, fungi, and green algae. While microbial (type 1) and animal (type 2) rhodopsins have no sequence similarity with each other, they share a common architecture consisting of seven-transmembrane alpha-helices (TM) connected by extracellular loops and intracellular loops. Both types of rhodopsins consist of opsin and a covalently attached retinal (the aldehyde of vitamin A), a photoreactive chromophore, via a protonated Schiff base linkage to an amino group of lysine in the middle of the seventh transmembrane helix (TM7). Upon the absorption of light, microbial rhodopsins undergo light-induced photoisomerization of all-trans retinal into the 13-cis isomer, whereas the photoisomerization of 11-cis retinal to all-trans isomer occurs in the animal rhodopsins. While animal visual rhodopsins are activated by light to catalyze GDP/GTP exchange in the alpha subunit of the retinal G protein transducin (Gt), microbial rhodopsins do not activate G proteins, but instead can function as light-dependent ion pumps, cation channels, and sensors. Pssm-ID: 320369 Cd Length: 219 Bit Score: 37.69 E-value: 4.66e-03
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