title: Direct binding of the human homologue of the Drosophila disc large tumor suppressor gene to seven-pass transmembrane proteins, tumor endothelial marker 5 (TEM5), and a novel TEM5-like protein.
abstract: The human homologue of the Drosophila discs large tumor suppressor gene (hDlg) is a member of the membrane-associated guanylate kinase family with three PSD-95/Dlg/ZO-1 (PDZ) domains. hDlg has been shown to bind tumor suppressor proteins, adenomatous polyposis coli (APC) and protein tyrosine phosphatase and tensin homologue (PTEN), and several viral oncoproteins, and has been implicated in the negative regulation of cell proliferation. hDlg has furthermore been shown to localize at the plasma membrane of synapses and to scaffold cell surface receptors and channels. In epithelial cells, hDlg localizes at the basolateral plasma membrane, but its localization mechanism is unknown. We searched here for a transmembrane protein that directly bound to hDlg. hDlg bound tumor endothelial marker 5 (TEM5), a seven-pass transmembrane protein that is homologous to the family B of G-protein-coupled receptors (GPCRs). TEM5 has previously been reported to display elevated expression during tumor angiogenesis and neoangiogenesis. The PDZ domains of hDlg bound the C-terminal PDZ-binding motif of TEM5. The expression of TEM5 was detected in endothelial cells of embryonic liver, where hDlg colocalized with TEM5. hDlg furthermore bound a novel seven-pass transmembrane protein, which was homologous to TEM5, and was named here a TEM5-like protein (TEM5-like). These results suggest that hDlg localizes at the plasma membrane through TEM5 and TEM5-like and furthermore scaffolds these GPCRs in endothelial cells during tumor angiogenesis and neoangiogenesis.
authors.affiliation: Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita 565-0871, Japan.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Irie
authors.forename: Masanori
authors.initials: M
authors.lastname: Asada
authors.forename: Akihisa
authors.initials: A
authors.lastname: Mino
authors.forename: Kenji
authors.initials: K
authors.lastname: Mandai
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Takai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D000074288:Discs Large Homolog 1 Protein; D004330:Drosophila / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C513314:DLG1 protein, human; D000074288:Discs Large Homolog 1 Protein; D029721:Drosophila Proteins; D008565:Membrane Proteins; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; C070350:dlg1 protein, Drosophila