Sandbox Reserved 819: Difference between revisions
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Archaerhodopsin-2 consists of the protein moiety rhodopsin and a reversibly covalently bound cofactor, retinal. | Archaerhodopsin-2 consists of the protein moiety rhodopsin and a reversibly covalently bound cofactor, the retinal. | ||
The trimeric structure functions as a light-driven proton pump thanks to | The trimeric structure functions as a light-driven proton pump thanks to this retinal molecule, called <scene name='56/568017/New_scene_ret_2/1'>RET</scene>, which changes its conformation when absorbing a photon, resulting in a conformational change of the surrounding protein and the proton pumping action. | ||
Others ligands are linked with each subunit of the trimeric structure like the bacterioruberin (<scene name='56/568017/22b/1'>22B</scene>). THe bacterioruberin plays a structural role for the trimerization of aR2. Several saccharides are also linked to the trimeric structure. | |||
Some lipids and glycolipids interact with the trimeric structure like the 2,3-di-phytanyl-glycerol (<scene name='56/568017/New_scene_3/1'>L2P</scene>) . They fill the intratrimer hydrophobic space and they are required to the complex activity. Others lipids surround the trimeric structure, which is essential to preserve it.<ref>PMID:18082767</ref> | Some lipids and glycolipids interact with the trimeric structure like the 2,3-di-phytanyl-glycerol (<scene name='56/568017/New_scene_3/1'>L2P</scene>) . They fill the intratrimer hydrophobic space and they are required to the complex activity. Others lipids surround the trimeric structure, which is essential to preserve it.<ref>PMID:18082767</ref> | ||
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The protein <scene name='56/568017/Rhodopsin/1'>rhodopsin</scene> has 7 transmembrane alpha helices, embedded in the plasma membrane. These helices are connected to each other by protein loops. | The protein <scene name='56/568017/Rhodopsin/1'>rhodopsin</scene> has 7 transmembrane alpha helices, embedded in the plasma membrane. These helices are connected to each other by protein loops. | ||
The rhodopsin harvests energy from light to carry out metabolic processes using a non-chlorophyll-based pathway. | The rhodopsin harvests energy from light to carry out metabolic processes using a non-chlorophyll-based pathway. Thnks to the retinal, the light induces a phototactic response by interacting with transducer membrane-embedded proteins that have no relation to G proteins. There are four different rhodopsins with different structures: A, B, D, E. | ||
===Structure and functioning of the Retinal (RET)=== | ===Structure and functioning of the Retinal (RET)=== | ||
The retinal (C20 H28 O) is a photoreactive chromophore. | |||
The rhodopsin binds retinal [http://www.ebi.ac.uk/pdbe-srv/pdbechem/chemicalCompound/show/RET] | The rhodopsin binds retinal [http://www.ebi.ac.uk/pdbe-srv/pdbechem/chemicalCompound/show/RET] in a central pocket on the seventh helix by a covalent bond with the <scene name='56/568017/Lysine_221/1'>lysine residue 221</scene>. Others bonds exist like van-der-waals bonds [http://www.ebi.ac.uk/pdbe-site/pdbemotif/?tab=boundmolecule&pdb=2z55&ligandCode3letter=RET]. | ||
Retinal is a polyene chromophore and allows to convert light into metabolic energy. It absorbs visible light maximally at 550-570 nm. | Retinal is a polyene chromophore and allows to convert light into metabolic energy. It absorbs visible light maximally at 550-570 nm. | ||
