title: Association of membrane-associated guanylate kinase-interacting protein-1 with Raf-1.
abstract: Membrane-associated guanylate kinase-interacting protein (MAGUIN)-1 was identified as a protein interacting with synaptic scaffolding molecule (S-SCAM) and postsynaptic density (PSD)-95/synapse-associated protein (SAP)90. MAGUIN-1 has a chimerical molecular structure composed of one sterile alpha motif, one PSD-95/Dlg-A/ZO-1 (PDZ), and one pleckstrin homology (PH) domain, and interacts with the PDZ domains of S-SCAM and PSD-95/SAP90 via its carboxyl-terminal PDZ-binding motif. MAGUIN-1 is considered as a mammalian homologue of Drosophila CNK, which is a Raf-interacting protein implicated in the regulation of eye development. Here we have tested whether MAGUIN-1 interacts directly with Raf-1. MAGUIN-1 and Raf-1 were coimmunoprecipitated from rat brain. MAGUIN-1 binds to the kinase domain of Raf-1, and Raf-1 binds to the middle region of MAGUIN-1 containing the PH domain. However, in contrast to the dominant active mutant of Ki-Ras, which interacts with Raf-1, recruits it to the plasma membrane from the cytosol, and activates it, MAGUIN-1 neither activates Raf-1 nor recruits it to the plasma membrane. MAGUIN-1 may link Raf-1 to components of synapses assembled by PSD-95/SAP90 and S-SCAM.
authors.affiliation: Department of Medical Biochemistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Yao
authors.forename: T
authors.initials: T
authors.lastname: Ohtsuka
authors.forename: H
authors.initials: H
authors.lastname: Kawabe
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuura
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
authors.forename: Y
authors.initials: Y
authors.lastname: Hata
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism*; D006224:Cricetinae; D004789:Enzyme Activation; D005982:Glutathione Transferase / Q000378:metabolism; D066298:In Vitro Techniques; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011485:Protein Binding; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D051381:Rats
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C118898:Cnksr2 protein, rat; D009419:Nerve Tissue Proteins; D005982:Glutathione Transferase; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases