Make Mfrp mutant mice attractive for delineating the mechanism that underlie MFRP/Mfrp-associated ocular disease and its genetic variability, which are poorly understood. Within the eye, MFRP is exclusively localized to the apical surface of the retinal pigment epithelium and the ciliary body epithelium. The protein has been suggested to play a role in the normal development as well as maintenance of photoreceptor outer segments. MFRP is a type II transmembrane protein and contains multiple domains, including an N-terminal cytoplasmic domain, a transmembrane domain, two extracellular cubulin domains, a low-density lipoprotein domain and a C-terminal cysteine-rich domain. Complement C1q tumor necrosis factor–related protein 5 is expressed from the same dicistronic transcript as Mfrp. Dicistronic messages often function in common pathways. Therefore, it is notable that MFRP and C1QTNF5 co-localize in the posterior eye and have been shown to interact directly by two-hybrid and biochemical studies. The functional consequence of this interaction, however, is Selumetinib unknown, and other potentially interacting partners of MFRP remain to be identified. Broadly, our findings delineate a potential role of MFRP in postnatal development and/or maintenance of the posterior eye, and provide evidence that MFRP and PRSS56 participate in the same functional pathway. Mouse models of retinal degeneration, in which the causative gene has been identified, are important tools for translational vision research, as they allow for in-depth study of cellular and molecular changes during development and disease progression. Such studies are especially important when the underlying function of the disrupted protein and molecular basis of the disease or pathology is unknown. Mutations in human MFRP and mouse Mfrp lead to retinal degeneration in both species and have been associated with a decrease in axial length in humans. Although nanophthalmia in Mfrp mutants has not been observed, posterior microphthalmia has yet to be assessed. The localization of MFRP to the RPE cell and ciliary body, suggests a potential role in posterior eye homeostasis, however, its function is unclear, and the molecular mechanisms by which mutations of this protein cause disease pathology are unknown. Decreased accumulation of phototransduction pathway transcripts has been documented in other retinal degeneration models. However, these studies may not be directly comparable to ours, since the disease models were analyzed at ages when ONL thickness was significantly decreased or photoreceptor outer segments were absent. The CUB domains, found in MFRP, are prevalent in genes that are developmentally regulated. The CRD domain in MFRP has a high homology to the Frizzled family of proteins, which are normally involved in Wnt signaling and are important in RPE development.