title: nRap GEP: a novel neural GDP/GTP exchange protein for rap1 small G protein that interacts with synaptic scaffolding molecule (S-SCAM).
abstract: Synaptic scaffolding molecule (S-SCAM) has six PDZ domains through which it interacts with N-methyl-d-aspartate receptors and neuroligin at synaptic junctions. We isolated here a novel S-SCAM-binding protein. This protein has one PDZ, one Ras association, one Ras GDP/GTP exchange protein (Ras GEP) domain, and one C-terminal consensus motif for binding to PDZ domains. We named it nRap GEP (neural Rap GEP). nRap GEP moreover has an incomplete cyclic AMP (cAMP)-binding (CAB) domain. The domain organization of nRap GEP is similar to that of Epac/cAMP-guanine nucleotide exchange factor (GEF) I, except that Epac/cAMP-GEFI has complete CAB and Ras GEP domains but lacks the other two domains and the C-terminal motif. nRap GEP showed GEP activity for Rap1 but did not bind cAMP. nRap GEP was specifically expressed in rat brain. Immunohistochemical analysis revealed that nRap GEP and S-SCAM were localized at synaptic areas of the cerebellum. These results suggest that nRap GEP is a novel neural Rap1-specific GEP which is associated with S-SCAM.
authors.affiliation: Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita, 565-0871, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ohtsuka
authors.forename: Y
authors.initials: Y
authors.lastname: Hata
authors.forename: N
authors.initials: N
authors.lastname: Ide
authors.forename: T
authors.initials: T
authors.lastname: Yasuda
authors.forename: E
authors.initials: E
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: A
authors.initials: A
authors.lastname: Mizoguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D003001:Cloning, Molecular; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D051528:Guanylate Kinases; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D020662:Guanine Nucleotide Exchange Factors; C114103:Magi2 protein, rat; D009419:Nerve Tissue Proteins; C403525:RAPGEF2 protein, human; D011994:Recombinant Proteins; D051528:Guanylate Kinases; D019204:GTP-Binding Proteins