title: Topological analysis of small leucine-rich repeat proteoglycan nyctalopin.
abstract: Nyctalopin is a small leucine rich repeat proteoglycan (SLRP) whose function is critical for normal vision. The absence of nyctalopin results in the complete form of congenital stationary night blindness. Normally, glutamate released by photoreceptors binds to the metabotropic glutamate receptor type 6 (GRM6), which through a G-protein cascade closes the non-specific cation channel, TRPM1, on the dendritic tips of depolarizing bipolar cells (DBCs) in the retina. Nyctalopin has been shown to interact with TRPM1 and expression of TRPM1 on the dendritic tips of the DBCs is dependent on nyctalopin expression. In the current study, we used yeast two hybrid and biochemical approaches to investigate whether murine nyctalopin was membrane bound, and if so by what mechanism, and also whether the functional form was as a homodimer. Our results show that murine nyctalopin is anchored to the plasma membrane by a single transmembrane domain, such that the LRR domain is located in the extracellular space.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Pasano
authors.initials: P
authors.lastname: Bojang
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Gregg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003198:Computer Simulation; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011509:Proteoglycans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D008565:Membrane Proteins; D011509:Proteoglycans; C560879:nyctalopin protein, mouse