title: Characterization of the interaction between annexin I and profilin.
abstract: Annexin I belongs to a family of calcium-dependent phospholipid-binding and membrane-binding proteins. Although many of the biochemical properties and the three-dimensional structure of this protein are known, its true physiological roles have yet to be thoroughly defined. Its putative functions include participation in the regulation of actin microfilaments dynamics, proposed after the discovery of an interaction with actin. In accordance with this hypothesis, we found that annexin I can also interact with profilin. We used different methods, overlay and surface plasmon resonance (BIAcore), to measure the parameters of the association equilibrium, i.e. k(on), k(off) and k(d). The affinity of annexin I for profilin was between 10(7) M and 10(8) M. High concentrations of KCl did not prevent the interaction, although a slight decrease in affinity was observed. Calcium, a modulator of annexin I functions interfered only marginally with the association, in a manner comparable to magnesium. Proteins or compounds known to interact with annexin I or profilin were found to inhibit the annexin-I--profilin interaction when added in the reaction medium. Recombinant profilin exhibited a slightly lower affinity than natural platelet protein when measured with BIAcore. Due to the submembrane localisation of annexin I and the regulatory activity of profilin on the cytoskeleton, an interaction between annexin I and profilin may therefore be implicated in the regulation of some cellular functions, particularly those governing membrane-cytoskeleton dynamic organization.
authors.affiliation: Institut National de la Santé Et de la Recherche Médicale U431, Université de Montpellier II Montpellier, France.
authors.forename: M T
authors.initials: MT
authors.lastname: Alvarez-Martinez
authors.forename: J C
authors.initials: JC
authors.lastname: Mani
authors.forename: F
authors.initials: F
authors.lastname: Porte
authors.forename: C
authors.initials: C
authors.lastname: Faivre-Sarrailh
authors.forename: J P
authors.initials: JP
authors.lastname: Liautard
authors.forename: J
authors.initials: J
authors.lastname: Sri Widada
mesh_terms: D000199:Actins / Q000378:metabolism; D017305:Annexin A1 / Q000187:drug effects / Q000378:metabolism*; D001667:Binding, Competitive; D001681:Biological Assay / Q000379:methods; D015374:Biosensing Techniques; D003285:Contractile Proteins; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D008840:Microfilament Proteins / Q000187:drug effects / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism / Q000494:pharmacology; D051304:Profilins; D011398:Promethazine / Q000494:pharmacology; D011489:Protein Denaturation
chemical_list: D000199:Actins; D017305:Annexin A1; D003285:Contractile Proteins; D008840:Microfilament Proteins; D051304:Profilins; D017853:Phosphotransferases (Alcohol Group Acceptor); C068961:phosphatidylinositol 4,5-biphosphate kinase; D011398:Promethazine