Molecular characterization of the murine orthologue of the human retinal proteoglycan IPM 150

PURPOSE: We recently identified a family of novel human proteoglycans/glyco proteins that are major constituents of the human interphotoreceptor matrix . Two members of this family, designated IPM 150 and IPM 200, have been ext ensively characterized. Although the IPM is thought to mediate crucial role s in retinal physiology, including retinal adhesion and photoreceptor cell viability, little is known about the roles of specific IPM constituents in these processes. In order to characterize the mouse IPM 150 orthologue, to initiate functional in vivo studies, and as a prerequisite towards future g enetic manipulation, we cloned the murine orthologue of human IPM 150 and d etermined its chromosomal location. METHODS: A mouse retinal cDNA library was screened using an IMAGE clone wit h sequence similarity to human IPM 150. The genomic location of the mouse I PM 150 gene was determined by radiation hybrid analyses. RESULTS: We describe here the molecular structure of the murine orthologue of human IPM 150 and place the location of its gene on mouse chromosome 9. Among the tissues examined, expression of IPM 150 appeared to be restricted to the retina. CONCLUSIONS: Comparison of the human and murine IPM 150 core proteins revea led that the molecules are generally well conserved, although several poten tially significant differences do exist. In addition, two highly conserved domains within the core proteins were identified. The data presented here r epresent a first step towards the development of experimental murine models , which may eventually be used to elucidate the mechanisms underlying retin al adhesion and photoreceptor survival.