| Arrestin-1 and arrestin-4, termed rod and cone arrestin, are expressed in photoreceptor cells and terminate rhodopsin and cone opsin signaling. |
| The opsin sequences have 364 amino acids divided into six exons separated by five 'neutral' segments or introns. |
| Rhodopsin consists of a protein called opsin bonded to a pigment called retinal. |
| Five classes of opsin genes encode visual pigments for dim-light and color vision. |
| The transport of opsin to the outer segment of photoreceptor cells seems especially critical for viability of these cells. |
| In the pure-cone American chameleon retina, all visual opsins including rod opsin are expressed. |
