title: Characterization of MPP4, a gene highly expressed in photoreceptor cells, and mutation analysis in retinitis pigmentosa.
abstract: Membrane-associated guanylate kinase (MAGUK) proteins are cell-cell contact organizing molecules that mediate targeting, clustering and anchoring of proteins at synapses and other cell junctions. MAGUK proteins may contain multiple protein-protein interaction motifs including PDZ, SH3 and guanylate kinase (GuK) domains. In this study, we performed a detailed analysis of the expression pattern of MPP4, a recently described member of the MAGUK protein family. We confirmed that this gene is highly expressed in retina, and demonstrate that it is also present, at lower levels, in brain. We identified a new retina specific isoform encoding a predicted protein lacking 71 amino acids. This protein region contains a newly identified L27 domain, another module playing a role in protein-protein interaction. By RNA in situ hybridization, Mpp4 expression was found to be localized to photoreceptor cells in postnatal retina. The MPP4 gene is localized to chromosome 2, in band 2q31-33, where a locus for autosomal recessive retinitis pigmentosa (RP26) has been mapped. Mutation analysis of the entire open reading frame of the MPP4 gene in a RP26 family revealed no pathologic mutations. In addition, we did not identify mutations in a panel of 300 unrelated patients with retinitis pigmentosa.
authors.affiliation: Telethon Institute of Genetics and Medicine (TIGEM), Via Pietro Castellino 111, 80129, Naples, Italy.
authors.forename: Ivan
authors.initials: I
authors.lastname: Conte
authors.forename: Marta
authors.initials: M
authors.lastname: Lestingi
authors.forename: Anneke
authors.initials: A
authors.lastname: den Hollander
authors.forename: Maria Giuseppina
authors.initials: MG
authors.lastname: Miano
authors.forename: Giovanna
authors.initials: G
authors.lastname: Alfano
authors.forename: Diego
authors.initials: D
authors.lastname: Circolo
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Pugliese
authors.forename: Francesco
authors.initials: F
authors.lastname: Testa
authors.forename: Francesca
authors.initials: F
authors.lastname: Simonelli
authors.forename: Ernesto
authors.initials: E
authors.lastname: Rinaldi
authors.forename: Montserrat
authors.initials: M
authors.lastname: Baiget
authors.forename: Sandro
authors.initials: S
authors.lastname: Banfi
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ciccodicola
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000201:enzymology / Q000378:metabolism; D002478:Cells, Cultured; D017124:Conserved Sequence / Q000235:genetics; D004252:DNA Mutational Analysis; D019143:Evolution, Molecular; D005136:Eye Proteins; D015971:Gene Expression Regulation, Enzymologic; D051528:Guanylate Kinases; D006801:Humans; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009703:Nucleoside-Phosphate Kinase / Q000235:genetics*; D010786:Photoreceptor Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000201:enzymology / Q000378:metabolism; D012174:Retinitis Pigmentosa / Q000201:enzymology / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
chemical_list: D005136:Eye Proteins; D008565:Membrane Proteins; D012313:RNA; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; C470950:MPP4 protein, human