Properties of the ipRGC Photopigment: Melanopsin Essay

859 Words 4 Pages
Properties of the ipRGC Photopigment: Melanopsin

IpRGC’s are unique in that they contain their own photopigment, melanopsin (source). Melanopsin is categorized in the opsin family because of its ability to receive a photon of light and translate it into an electrochemical signal. This ability has been observed and is well understood in the photoreceptor rods and cones. The photoreceptors are key players in translating visual stimuli to a language the brain can understand. Their ability to interpret visual cues on their own depends on the opsins that are integrated into their structure (SOURCE). Comparing photoreceptor opsins and the opsin expressed in ipRGC’s is helpful because they both act to relay signals to the brain. The pathway
…show more content…
Retinal then converts the absorbed light into energy by initiating a conformational change. The positively charged schiff base linkage is balanced by the negative charge in the third transmembrane domaine (davies). The third cytoplasmic loop of melanopsin shows poor conservation when compared to other opsins through an amino acid alignment (davies). This suggests that melanopsin can activate the phototransduction cascade without high amino acid conservation. Melanopsin also has a distinct genomic structure and forms its own branch in the GPCR family (davies sources?). The poor amino acid conservation and distinct structure indicate melanopsin behaves differently than other opsins and is also evolutionarily unique. ... if we know more about them we can help fix them

Structural and Functional Properties of ipRGCs Involved in the Phototransduction Process

Light detection in the eye begins when 11-cis retinal absorbs a photon and photoisomerises? to the all-trans state. This conformational change of the chromophore then changes the configuration of the opsin which allows the photopigment to interact with the G protein, triggering a phototranduction cascade and finally changing the receptor membrane potential (davies 30). The photopigment in this case will be melanopsin but the exact pathway causing action potential to be transmitted is not known for certain. As mentioned before, melanopsin more closely resembles invertebrate

Related Documents