title: beta(1) integrin binds the 16-kDa subunit of vacuolar H(+)-ATPase at a site important for human papillomavirus E5 and platelet-derived growth factor signaling.
abstract: Integrins mediate adhesive interactions between cells and the extracellular matrix, and play a role in cell migration, proliferation, differentiation, cytoskeletal organization, and signal transduction. We have identified an interaction between the beta(1) integrin and the 16-kDa subunit of vacuolar H(+)-ATPase (16K). This interaction was first isolated in a yeast two-hybrid screen and confirmed by coimmunoprecipitation and in in vitro binding assays using bacterially expressed proteins. Immunofluorescent studies performed in L6 myoblasts expressing both native and epitope-tagged 16K demonstrate co-localization with beta(1) integrin in focal adhesions. Deletion of the fourth of four transmembrane helices in 16K results in loss of interaction with beta(1) integrin in vitro and in the two-hybrid system, and less prominent staining in focal adhesions. This helix is also required for ligand-independent activation of platelet-derived growth factor-beta receptor signaling by the human papillomavirus E5 oncoprotein. Overexpression of 16K or expression of 16K lacking this helix alters the morphology of myoblasts and fibroblasts, suggesting that the interaction of 16K with integrins could be important for cell growth control. We also discuss the possible role 16K might play in integrin movement.
authors.affiliation: Department of Molecular Biology and Genetics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Skinner
authors.forename: A G
authors.initials: AG
authors.lastname: Wildeman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D000939:Epitopes / Q000737:chemistry; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured; D025262:Vacuolar Proton-Translocating ATPases; D000086082:Viroporin Proteins
chemical_list: D017931:DNA Primers; D000939:Epitopes; D019012:Integrin beta1; D009856:Oncogene Proteins, Viral; D010982:Platelet-Derived Growth Factor; D006180:Proton-Translocating ATPases; D011993:Recombinant Fusion Proteins; D025262:Vacuolar Proton-Translocating ATPases; C054859:oncogene protein E5, Human papillomavirus type 16; D000086082:Viroporin Proteins