title: Annexin-V binds to the intracellular part of the beta(5) integrin receptor subunit.
abstract: Bovine lactadherin binds to the alpha(v)beta(3) and alpha(v)beta(5) integrins in an RGD-dependent manner and also to anionic phospholipids. During the affinity purification of lactadherin binding receptors, a 35-kDa protein persistently coeluted with the alpha(v)beta(5) integrin receptor. Subsequently, peptide mapping, amino acid sequencing, and mass spectrometry analysis identified this protein as bovine annexin-V. Annexin-V accompanied the integrin receptor eluted with either RGD peptide or with EDTA suggesting that annexin-V bound specifically to the alpha(v)beta(5) integrin. To further investigate this putative interaction of annexin-V with the alpha(v)beta(5) integrin receptor, human annexin-V and intracellular domains of the human alpha(v)beta(5) integrin subunits were used in ligand blotting assays. Radiolabeled annexin-V showed weak binding to the intracellular part of beta(5) integrin subunit. However, by adding the aminophospholipid, phosphatidyl serine, the interaction with the beta(5) cytoplasmic peptide was enhanced many fold. Furthermore, the interaction was shown to be independent of phosphorylation, as annexin-V bound to unphosphorylated beta(5) peptide at a similar level to the phosphorylated peptide. Since binding of annexin-V to the alpha(v) integrin subunit tail was not detected, annexin-V was shown to associate specifically with the beta(5) cytoplasmic tail. Together these findings suggest a novel link between annexins and the integrin receptor family.
authors.affiliation: Protein Chemistry Laboratory, Department of Molecular and Structural Biology, University of Aarhus, Aarhus C, Denmark.
authors.forename: Mikkel H
authors.initials: MH
authors.lastname: Andersen
authors.forename: Lars
authors.initials: L
authors.lastname: Berglund
authors.forename: Torben E
authors.initials: TE
authors.lastname: Petersen
authors.forename: Jan T
authors.initials: JT
authors.lastname: Rasmussen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017304:Annexin A5 / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism; D000954:Antigens, Surface / Q000378:metabolism; D001665:Binding Sites; D002417:Cattle; D002846:Chromatography, Affinity; D039564:Integrin alphaV; D039641:Integrin beta Chains; D016023:Integrins / Q000737:chemistry* / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D017304:Annexin A5; D015703:Antigens, CD; D000954:Antigens, Surface; D039564:Integrin alphaV; D039641:Integrin beta Chains; D016023:Integrins; D008894:Milk Proteins; C084344:integrin beta5