title: The carboxyl terminal mutational hotspot of the ciliary disease protein RPGRORF15 (retinitis pigmentosa GTPase regulator) is glutamylated in vivo.
abstract: Mutations inRPGR(ORF15)(retinitis pigmentosa GTPase regulator) are a major cause of inherited retinal degenerative diseases. RPGR(ORF15)(1152 residues) is a ciliary protein involved in regulating the composition and function of photoreceptor cilia. The mutational hotspot in RPGR(ORF15)is an unusual C-terminal domain encoded by exon ORF15, which is rich in polyglutamates and glycine residues (Glu-Gly domain) followed by a short stretch of basic amino acid residues (RPGR(C2)domain; residues 1072-1152). However, the properties of the ORF15-encoded domain and its involvement in the pathogenesis of the disease are unclear. Here we show that RPGR(ORF15)is glutamylated at the C-terminus, as determined by binding to GT335, which recognizes glutamylated substrates. This reactivity is lost in two mouse mutants ofRpgr, which do not express RPGR(ORF15)due to disease-causing mutations in exon ORF15. Our results indicate that RPGR(ORF15)is posttranslationally glutamylated in the Glu-Gly domain and that the GT335 antibody predominantly recognizes RPGR(ORF15)in photoreceptor cilia.
authors.affiliation: Department of Ophthalmology, Horae Gene Therapy Center, UMASS Medical School, Worcester, MA 01605, USA.
authors.forename: Kollu N
authors.initials: KN
authors.lastname: Rao
authors.affiliation: Department of Ophthalmology, Horae Gene Therapy Center, UMASS Medical School, Worcester, MA 01605, USA.
authors.forename: Manisha
authors.initials: M
authors.lastname: Anand
authors.affiliation: Department of Ophthalmology, Horae Gene Therapy Center, UMASS Medical School, Worcester, MA 01605, USA Hemant.khanna@umassmed.edu.
authors.forename: Hemant
authors.initials: H
authors.lastname: Khanna
keywords: Cilia; GT335; Glutamylation; RPGR; Retina