title: Brain-specific potential guanine nucleotide exchange factor for Arf, synArfGEF (Po), is localized to postsynaptic density.
abstract: We cloned from a rat brain cDNA library a novel cDNA and named it a potential synaptic guanine nucleotide exchange factor (GEF) for Arf (synArfGEF (Po)) (GenBank Accession no. AB057643) based on its domain structure and localization. The cloned gene was 7410 bases long with a 3585-bp coding sequence encoding a protein of 1194 amino acids. The deduced protein contained a coiled-coil structure in the N-terminal portion followed by Sec7 and Plekstrin homology (PH) domains. Thus, the protein was a member of the Sec7 family of proteins, GEFs. Conservation of the ADP-ribosylation factor (Arf)-binding sequence suggested that the protein was a GEF for Arf. The gene was expressed specifically in the brain, where it exhibited region-specific expression. The protein was highly enriched in the postsynaptic density (PSD) fraction prepared from the rat forebrain. Uniquely, the protein interacted with PSD-95, SAP97 and Homer/Vesl 1/PSD-Zip45 via its C-terminal PDZ-binding motif and co-localized with these proteins in cultured cortical neurons. These results supported its localization in the PSD. The postsynaptic localization was also supported by immunohistochemical examination of the rat brain. The mRNA for the synArfGEF was also localized to dendrites, as well as somas, of neuronal cells. Thus, both the mRNA and the protein were localized in the postsynaptic compartments. These results suggest a postsynaptic role of synArfGEF in the brain.
authors.affiliation: Department of Neuroplasticity, Research Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Inaba
authors.forename: Qing Bao
authors.initials: QB
authors.lastname: Tian
authors.forename: Akira
authors.initials: A
authors.lastname: Okano
authors.forename: Jing-Ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakagami
authors.forename: Shoko
authors.initials: S
authors.lastname: Miyazawa
authors.forename: Weidong
authors.initials: W
authors.lastname: Li
authors.forename: Atsushi
authors.initials: A
authors.lastname: Komiyama
authors.forename: Kaoru
authors.initials: K
authors.lastname: Inokuchi
authors.forename: Hisatake
authors.initials: H
authors.lastname: Kondo
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003712:Dendrites / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics* / Q000378:metabolism*; D000072233:Homer Scaffolding Proteins; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism; D009928:Organ Specificity; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D013569:Synapses / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D000076122:Disks Large Homolog 4 Protein; C501119:Dlg1 protein, rat; C501449:Dlg4 protein, rat; D020662:Guanine Nucleotide Exchange Factors; D000072233:Homer Scaffolding Proteins; C000606624:Homer1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; C000654189:Iqsec3 protein, rat; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D012333:RNA, Messenger; C033652:postsynaptic density proteins; D020727:ADP-Ribosylation Factors