title: IQ-ArfGEF/BRAG1 is associated with synaptic ribbons in the mouse retina.
abstract: IQ-ArfGEF/BRAG1 is a guanine nucleotide exchange factor for ADP ribosylation factors (Arfs), which are implicated in membrane trafficking and actin cytoskeleton dynamics. In this study, we examined the immunohistochemical localization of IQ-ArfGEF/BRAG1 in the adult mouse retina using light and electron microscopy. IQ-ArfGEF/BRAG1 was distributed in a punctate manner and colocalized well with RIBEYE in both the outer and inner plexiform layers. Immunoelectron microscopic analysis showed that IQ-ArfGEF/BRAG1 was localized at the synaptic ribbons of photoreceptors. When heterologously expressed in HeLa cells, IQ-ArfGEF/BRAG1 was recruited to RIBEYE-containing clusters and formed an immunoprecipitable complex with RIBEYE. Furthermore, immunoprecipitation analysis showed that anti-IQ-ArfGEF/BRAG1 antibody efficiently pulled down RIBEYE from retinal lysates. These findings indicate that IQ-ArfGEF/BRAG1 is a novel component of retinal synaptic ribbons and forms a protein complex with RIBEYE.
authors.affiliation: Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Kanagawa 228-8555, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Katsumata
authors.forename: Naoki
authors.initials: N
authors.lastname: Ohara
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tamaki
authors.forename: Tomoko
authors.initials: T
authors.lastname: Niimura
authors.forename: Hideaki
authors.initials: H
authors.lastname: Naganuma
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakagami
mesh_terms: D000429:Alcohol Oxidoreductases; D000818:Animals; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D015870:Gene Expression / Q000502:physiology; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D051528:Guanylate Kinases; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure*; D014162:Transfection / Q000379:methods
chemical_list: D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D020662:Guanine Nucleotide Exchange Factors; C539984:IQSEC2 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D000429:Alcohol Oxidoreductases; C111341:Ctbp2 protein, mouse; D051528:Guanylate Kinases