title: p55 protein is a member of PSD scaffold proteins in the rat brain and interacts with various PSD proteins.
abstract: p55 is a membrane-associated guanylate kinase (MAGuK) family member that consists of a single PDZ followed by SH3, HOOK and guanylate kinase (GuK or GK) domains. We investigated rat p55 (r-p55) in the brain. r-p55 mRNA was expressed widely in various tissues and in various regions of the brain. r-p55 protein was also expressed widely in various rat tissues, including brain and erythrocytes. The protein was enriched in the synaptic plasma membrane and postsynaptic density (PSD) fractions of the forebrain. An immunocytochemical study using cultured cortical neurons suggested postsynaptic localization of r-p55 protein. Pull-down assay showed that r-p55 protein interacted with r-p55 itself and various PSD proteins, such as PSD-95, SAP97, GKAP, CASK, GRIP, neuroligin, cadherin, tubulin, actin, alpha-internexin, neurofilament-L and Ca(2+)/calmodulin-dependent protein kinase II, through its PDZ, SH3, HOOK or GK domains. The interaction with PSD-95 was found to occur between the PDZ domains of PSD-95 and the HOOK and GK domains of r-p55 protein. These findings, together with the presence of r-p55 puncta in a period of early synaptogenesis, suggest that r-p55 protein functions as one of postsynaptic scaffold component in an early stage of synaptogenesis in the brain. r-p55 protein may form a basic structure, which interlinks diverse functional molecules of the PSD necessary for postsynaptic signaling and synaptic adhesion.
authors.affiliation: Department of Neuroplasticity, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Jing-Ping
authors.forename: Qing-Bao
authors.initials: QB
authors.lastname: Tian
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakagami
authors.forename: Hisatake
authors.initials: H
authors.lastname: Kondo
authors.forename: Shogo
authors.initials: S
authors.lastname: Endo
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D000918:Antibody Specificity; D015152:Blotting, Northern; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular / Q000379:methods; D018076:DNA, Complementary / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D004622:Embryo, Mammalian; D005455:Fluorescent Antibody Technique / Q000379:methods; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D051528:Guanylate Kinases; D047468:Immunoprecipitation / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008565:Membrane Proteins; D046912:Multiprotein Complexes / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000145:classification / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D016708:Synaptophysin / Q000378:metabolism; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C501451:Mpp2 protein, rat; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016708:Synaptophysin; C033652:postsynaptic density proteins; C106868:CASK kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D051528:Guanylate Kinases