Sandbox Reserved 1451

Rhodopsin

Rhodopsin is a member of the G-protein coupled receptor (GPCR) family. Rhodopsin is the common GPCR structure used to understand functionality of G-protein coupled receptors. Rhodopsin is commonly found in the photoreceptors in the retina, specifically in the rod photoreceptors and become activated by photons of light. Rhodopsin contains a chromophore (compound that absorbs light), specifically 11-cis-retinal, which when active recruites G proteins to transmit a signaling cascade in neural impulses to the gray matter of the occipital lobe. Once the receptor has been activated, a new rhodopsin needs to be regenerated. Rhodopsin is located in the rod outer segment (ROS) which consists of stacked disks enclosed by a membrane. The entire family of GPCR’s have the common structure of seven alpha-helices across membranes. Rhodopsin’s structure changes upon photoactivation. The sixth helix bends away from the seventh creating a pocket that allows for binding of a G protein. A salt bridge covers this pocket until the helices shift away from one another. Once the G protein has bound then the signal can be transmitted to the occipital lobe. Over 120 point mutations to rhodopsin have been identified which can lead to night blindness and more several visual problems^[1].

Function

ghwapfj

Disease

Relevance

Structural highlights

This is rhodopsin without any ligand bound. This is the ligand that rhodopsin binds This is rhodopsin with ligand bound

</StructureSection>

References

1. ↑ Zhou XE, Melcher K, Xu HE. Structure and activation of rhodopsin. Acta Pharmacol Sin. 2012 Mar;33(3):291-9. doi: 10.1038/aps.2011.171. Epub 2012, Jan 23. PMID:22266727 doi:http://dx.doi.org/10.1038/aps.2011.171