Protein XRP2 is a protein that in humans is encoded by the RP2 gene. It is mapped to Xp11.3. The RP2 locus has been implicated as one cause of X-linked retinitis pigmentosa. The predicted gene product shows homology with human cofactor C, a protein involved in the ultimate step of beta-tubulin folding. Progressive retinal degeneration may therefore be due to the accumulation of incorrectly folded photoreceptor or neuron-specific tubulin isoforms followed by progressive cell death. The RP2 protein is also involved in regulating the function and extension of outer segment of cone photoreceptors in mice.