User:Eduardo Araujo Silva/Sandbox 1
From Proteopedia
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==Orco== | ==Orco== | ||
<StructureSection load='6c70' size='340' side='right' caption='Cryo-EM structure of Orco homotetramer from the parasitic fig wasp Apocrypta bakeri at 3.5 Å resolution [[6c70]]' scene=''> | <StructureSection load='6c70' size='340' side='right' caption='Cryo-EM structure of Orco homotetramer from the parasitic fig wasp Apocrypta bakeri at 3.5 Å resolution [[6c70]]' scene=''> | ||
| - | Orco is the co-receptor of insect odorant receptors (ORs), expressed in olfactory sensory neurons (OSNs) from insects antennae. Its structure and function are highly conserved across insect species. | + | Orco is the co-receptor of insect odorant receptors (ORs), expressed in olfactory sensory neurons (OSNs) from insects antennae <ref>doi:10.1016/j.neuron.2004.08.019</ref>. Its structure and function are highly conserved across insect species <ref>PMID: 15723778</ref>. |
== Function == | == Function == | ||
| - | Orco is essential for the function and membrane localization of ORs. This co-receptor binds to a specific odorant receptor (ORx) on the membrane of OSNs, forming a heteromeric complex. Thus, the ORx/Orco complex functions as a non-selective cation channel, with ORx ensuring the specificity of odor and pheromones ligands that activate the channel, contributing to signal transduction which results in behavioral changes. In the absence of an ORx, Orco is also capable of forming functional channels activated by VUAA1. | + | Orco is essential for the function, assemble and membrane localization of ORs. This co-receptor binds to a specific odorant receptor (ORx) on the membrane of OSNs, forming a heteromeric complex. Thus, the ORx/Orco complex functions as a non-selective cation channel, with ORx ensuring the specificity of odor and pheromones ligands that activate the channel, contributing to signal transduction which results in behavioral changes <ref>PMID: 16402857</ref><ref>doi:10.1016/j.neuron.2004.08.019</ref>. In the absence of an ORx, Orco is also capable of forming functional channels activated by VUAA1 <ref>PMID: 21555561</ref>. |
== Structural highlights == | == Structural highlights == | ||
| - | In the absence of an ORx, Orco is capable of forming a <scene name='10/1050291/Homotetramer/1'>homotetramer</scene>, with four subunits encircling a channel. Each <scene name='10/1050291/Subunit/1'>subunit</scene> is composed of 7 transmembrane helices (S1-S7), an intracellular <FONT COLOR="blue">'''N-terminus'''</FONT> and an extracellular <FONT COLOR="red">'''C-terminus'''</FONT>. The majority of the protein is intramembranous, while <scene name='10/1050291/Small_loops/1'>small loops</scene> are exposed to the extracellular environment, and a small intracellular domain, called the anchor domain, extends into the cytoplasm. The anchor domain is named as such because its where the majority of <scene name='10/1050291/Inter-subunit_interaction/1'>inter-subunit interactions</scene> resides and thus 'anchoring' the subunits within the lipid membrane. In the core of the anchor domain is S7a surrounded by S4, S5 and S6. The S1-S6 domains of each subunit are narrowly tethered to their respective S7b helix and are separated from the domains of the other subunits. Each subunit contributes with a <scene name='10/1050291/S7b/1'>S7b helix</scene> that lines the ion-conduction pathway. The pore is narrowest near the extracellular end, where two residues, Leu 473 and Val 469, forms a <scene name='10/1050291/Constriction/1'>constriction</scene>, preventing the passage of hydrated ions, which characterizes its closed state. | + | In the absence of an ORx, Orco is capable of forming a <scene name='10/1050291/Homotetramer/1'>homotetramer</scene>, with four subunits encircling a channel. Each <scene name='10/1050291/Subunit/1'>subunit</scene> is composed of 7 transmembrane helices (S1-S7), an intracellular <FONT COLOR="blue">'''N-terminus'''</FONT> and an extracellular <FONT COLOR="red">'''C-terminus'''</FONT>. The majority of the protein is intramembranous, while <scene name='10/1050291/Small_loops/1'>small loops</scene> are exposed to the extracellular environment, and a small intracellular domain, called the anchor domain, extends into the cytoplasm. The anchor domain is named as such because its where the majority of <scene name='10/1050291/Inter-subunit_interaction/1'>inter-subunit interactions</scene> resides and thus 'anchoring' the subunits within the lipid membrane. In the core of the anchor domain is S7a surrounded by S4, S5 and S6. The S1-S6 domains of each subunit are narrowly tethered to their respective S7b helix and are separated from the domains of the other subunits. Each subunit contributes with a <scene name='10/1050291/S7b/1'>S7b helix</scene> that lines the ion-conduction pathway. The pore is narrowest near the extracellular end, where two residues, Leu 473 and Val 469, forms a <scene name='10/1050291/Constriction/1'>constriction</scene>, preventing the passage of hydrated ions, which characterizes its closed state <ref>PMID: 30111839</ref>. |
</StructureSection> | </StructureSection> | ||
== References == | == References == | ||
<references/> | <references/> | ||
Revision as of 00:12, 2 June 2024
Orco
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References
- ↑ Larsson MC, Domingos AI, Jones WD, Chiappe ME, Amrein H, Vosshall LB. Or83b encodes a broadly expressed odorant receptor essential for Drosophila olfaction. Neuron. 2004 Sep 2;43(5):703-14. PMID:15339651 doi:http://dx.doi.org/10.1016/j.neuron.2004.08.019
- ↑ Jones WD, Nguyen TA, Kloss B, Lee KJ, Vosshall LB. Functional conservation of an insect odorant receptor gene across 250 million years of evolution. Curr Biol. 2005 Feb 22;15(4):R119-21. PMID:15723778 doi:10.1016/j.cub.2005.02.007
- ↑ Benton R, Sachse S, Michnick SW, Vosshall LB. Atypical membrane topology and heteromeric function of Drosophila odorant receptors in vivo. PLoS Biol. 2006 Feb;4(2):e20. PMID:16402857 doi:10.1371/journal.pbio.0040020
- ↑ Larsson MC, Domingos AI, Jones WD, Chiappe ME, Amrein H, Vosshall LB. Or83b encodes a broadly expressed odorant receptor essential for Drosophila olfaction. Neuron. 2004 Sep 2;43(5):703-14. PMID:15339651 doi:http://dx.doi.org/10.1016/j.neuron.2004.08.019
- ↑ Jones PL, Pask GM, Rinker DC, Zwiebel LJ. Functional agonism of insect odorant receptor ion channels. Proc Natl Acad Sci U S A. 2011 May 24;108(21):8821-5. PMID:21555561 doi:10.1073/pnas.1102425108
- ↑ Butterwick JA, Del Marmol J, Kim KH, Kahlson MA, Rogow JA, Walz T, Ruta V. Cryo-EM structure of the insect olfactory receptor Orco. Nature. 2018 Aug;560(7719):447-452. doi: 10.1038/s41586-018-0420-8. Epub 2018 Aug, 15. PMID:30111839 doi:http://dx.doi.org/10.1038/s41586-018-0420-8
