This gene encodes the delta subunit of rod-specific photoreceptor phosphodiesterase (PDE), a key enzyme in the phototransduction cascade. A similar protein in cow functions in solubilizing membrane-bound PDE. In addition to its role in the PDE complex, the encoded protein is thought to bind to prenyl groups of proteins to target them to subcellular organelles called cilia. Mutations in this gene are associated with Joubert syndrome-22. Alternative splicing results in multiple splice variants.