The K153Del PRPH2 mutation differentially impacts photoreceptor structure and function

Peripherin 2 (Prph2) is a photoreceptor tetraspanin, and deletion of codon 153 (K153 Delta) leads to retinitis pigmentosa, pattern dystrophy, and fundus flavimaculatus in the same family. To study this variability, we generated a K153 Delta-Prph2 knockin mouse. K153 Delta-Prph2 cannot form the complexes required for outer segment formation, and in cones cannot interact with its binding partner rod outer segment membrane protein 1. K153 Delta causes dominant defects in rod and cone function; however, rod but not cone ultrastructure is improved by the presence of K153 Delta-Prph2. Likewise, supplementation of K153 Delta heterozygotes with WT-Prph2 results in structural but not functional improvements. These results support the idea that mutations may differentially affect Prph2's role as a structural component, and its role as a functional protein key for organizing membrane domains for cellular signalling. These roles may be different in rods and cones, thus contributing to the pheno-typic heterogeneity that characterizes diseases associated with Prph2 mutations.