PRCD Is a Small Disc-Specific Rhodopsin-Binding Protein of Unknown Function.

PRCD (progressive rod-cone degeneration) is a small ~6 kDa protein with unknown function that specifically resides in photoreceptor discs and interacts with rhodopsin. PRCD's discovery resulted from decades-long study of a canine retinal disease called progressive rod-cone degeneration which is one of the most frequent causes of blindness in dogs characterized by the slow, progressive death of rod photoreceptors followed by cones. A series of genetic studies eventually mapped the disease to a single point mutation in a novel gene which was then named Prcd. Highlighting the importance of this gene, this and several other mutations have been identified in human patients suffering from retinitis pigmentosa. In this review, we highlight what is currently known about PRCD protein, including the etiology and pathology of the retinal disease caused by its mutation, the protein's trafficking, localization, and biochemical characterization.