Premium
Membrane‐associated guanylate kinase with inverted orientation (MAGI)‐1/brain angiogenesis inhibitor 1‐associated protein (BAP1) as a scaffolding molecule for Rap small G protein GDP/GTP exchange protein at tight junctions
Author(s) -
Mino Akihisa,
Ohtsuka Toshihisa,
Inoue Eiji,
Takai Yoshimi
Publication year - 2000
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2000.00385.x
Subject(s) - guanylate kinase , pdz domain , biology , adherens junction , scaffold protein , postsynaptic density , microbiology and biotechnology , septate junctions , rap1 , signal transducing adaptor protein , tight junction , transmembrane protein , membrane protein , signal transduction , receptor , postsynaptic potential , cell , biochemistry , gap junction , intracellular , cadherin , membrane
Membrane‐associated guanylate kinase (MAGUK) with inverted orientation (MAGI)‐1/brain angiogenesis inhibitor 1‐associated protein (BAP1), is a member of the MAGUK family that has multiple PDZ domains and interacts with many transmembrane proteins, including receptors and channels, through these domains. MAGI‐1/BAP1 is ubiquitously expressed and localized at tight junctions in epithelial cells. It is an isoform of the neurone‐specific synaptic scaffolding molecule (S‐SCAM), which is known to interact with NMDA receptors and neuroligins. We have recently found that S‐SCAM also interacts with a signalling molecule, a GDP/GTP exchange protein (GEP) that is specific for Rap1 small G protein, Rap GEP, which has also recently been referred to as RA‐GEF/PDZ‐GEFI/CNras‐GEF. In this study, we have examined whether MAGI‐1/BAP1 also interacts with and serves as a scaffolding molecule for Rap GEP at tight junctions in epithelial cells. MAGI‐1/BAP1 similarly interacted with Rap GEP in cell‐free and intact cell systems. A Northern blot analysis revealed that Rap GEP was expressed in most tissues examined. However, neither postsynaptic density (PSD)‐95/synapse‐associated protein (SAP) 90 (another member of the MAGUK family) nor SAP97/human discs‐large tumour suppressor gene product (another ubiquitously expressed MAGUK localizing to adherens junctions in epithelial cells and the isoform of PSD‐95/SAP90) interacted with Rap GEP. These results indicate that MAGI‐1/BAP1 serves as a scaffolding molecule for Rap GEP at tight junctions in epithelial cells.