PrBP/δ, encoded by the Pde6d gene, is an isoprenyl-binding protein that regulates trafficking of isoprenylated proteins, such as PDE6 and GRK1, from photoreceptor inner segments to outer segments. The human gene (PDE6D) encoding a new subunit (delta) has been characterized and mapped to the long arm of chromosome 2 (HSA2q35-q36) where a new autosomal recessive retinitis pigmentosa (arRP) locus (RP26) has been localized. Characterization of the canine PDE6D shows the gene is about 4.2kb containing four exons interrupted by three introns. Overexpression of PDE6D in mouse eyes caused elevated intraocular pressure (IOP), and this elevation was reversed by topical ocular application of either anecortave acetate (AA) or anecortave desacetate (AdesA). The identification of PDE6D as the molecular binding partner of AA provides insight into the role of this drug candidate in treating glaucoma.