Melanopsin was discovered as a novel opsin in the melanophores (light-sensitive skin cells) of the African clawed frog. It was then found that melanopsin is also present in mouse retina, specifically in ganglion cells, and that it mediates non-visual photoreceptive tasks. Melanopsin is also encoded by Opn4 with orthologs in a variety of organisms. Melanopsin-SAP specifically eliminates intrinsically photosensitive retinal ganglion cells (ipRGCs) that express melanopsin. The ipRGCs, with their amazing long processes, are involved in the perception of light and dark and are circadian rhythm determinants.
Melanopsin-SAP is a chemical conjugate of an affinity-purified rabbit polyclonal antibody to mouse melanopsin and the ribosome-inactivating protein, saporin. It specifically eliminates intrinsically photosensitive retinal ganglion cells (ipRGCs) that express melanopsin.