Sandbox 173: Difference between revisions

<applet load='1u19' size='300' color='black' frame='true' align='right' caption='11-cis Retinylidene Chromophore. The generated structures are from Chain A.'/>

Rhodopsin consists of an opsin [http://en.wikipedia.org/wiki/Apoprotein apoprotein] and a <scene name='Sandbox_173/11-cis_retinylidene_structure/1'>11-cis retinylidene chromophore</scene> in its active site. Rhodopsin is bound covalently to the 11-''cis'' retinal, the chromophore or "ligand," (shown in <font color='#FFFF00'>yellow</font>) and this retinal is found in deeply in the core of the helices, in a hydrophobic site, parallel to the lipid bilayer<ref name="Article19">PMID:16051215</ref>. Comparatively, it is situated more towards the extracellular planes of the membrane bilayer <ref name="Article12"/>. The retinal is attached in the active site of rhodopsin through a protonated Schiff base (an N-substituted imine) bond to the ε-amino group of Lysine 296 residue (shown in <font color='#00FF00'>green</font>) on the C-terminal Helix 7, with this linkage creating a positive charge on the chromophore <ref name="Article4"/>. The protonated Schiff base of rhodopsin is stabilized through <scene name='Sandbox_173/Glu113/1'>Glutamine 113</scene> residue electrostatic interaction with the counterion, holding the inactive rhodopsin in its state<ref name="Article20"/>.