Arrestin-1 was originally identified as the S-antigen (SAG) causing uveitis (autoimmune eye disease), then independently described as a 48 kDa protein that binds light-activated phosphorylated rhodopsin before it became clear that both are one and the same. It was later renamed visual arrestin, but when another cone-specific visual subtype was cloned the term rod arrestin was coined. This also turned out to be a misnomer: arrestin-1 expresses at comparable very high levels in both rod and cone photoreceptor cells.