title: High affinity interaction between histidine-rich glycoprotein and the cell surface type ATP synthase on T-cells.
abstract: Histidine-rich glycoprotein (HRG) is a plasma protein implicated in the innate immune system. In recent studies, we showed that either HRG, or the Arg23-Lys66 glycopeptide derived from HRG, in concert with concanavalin A (Con A), promotes a morphological change and adhesion of the human leukemic T-cell line MOLT-4 to culture dishes, and that cell surface glycosaminoglycan or Fcgamma receptors do not participate in this cellular event. In the present study, we identified the alpha-subunit of ATP synthase as one of the HRG-binding proteins on the surface of T-cells by HRG-derived glycopeptide affinity chromatography and by a peptide mass finger printing method. HRG specifically interacted with mitochondrial ATP synthase with a dissociation constant of 66 nM. The presence of alpha- and beta-subunits of ATP synthase on the plasma membrane of MOLT-4 cell was demonstrated by immunofluorescent staining and FACS analysis. The HRG/Con A-induced morphological changes of MOLT-4 cells were specifically inhibited by a monoclonal antibody against the beta-subunit of ATP synthase. These results strongly suggest that the cell surface ATP synthase functions as a binding protein for HRG on MOLT-4 cells, which is required for the morphological changes observed in MOLT-4 cells following treatment with HRG/Con A.
authors.affiliation: Department of Life Science, Graduate School of Life Science, University of Hyogo, Harima Science Garden City, Hyogo 678-1297, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ohta
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ikemoto
authors.forename: Ayako
authors.initials: A
authors.lastname: Usami
authors.forename: Takehiko
authors.initials: T
authors.lastname: Koide
authors.forename: Sadao
authors.initials: S
authors.lastname: Wakabayashi
mesh_terms: D000595:Amino Acid Sequence; D055592:Biophysical Phenomena; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D006801:Humans; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010449:Peptide Mapping; D011485:Protein Binding; D021122:Protein Subunits; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism*; D000099053:Histidine-Rich Glycoprotein
chemical_list: D010446:Peptide Fragments; D021122:Protein Subunits; D011506:Proteins; D000099053:Histidine-Rich Glycoprotein; D006180:Proton-Translocating ATPases