title: Cholesterol enhances phospholipid binding and aggregation of annexins by their core domain.
abstract: Annexins are Ca(2+)-dependent phospholipid-binding proteins composed of two domains: A conserved core that is responsible for Ca(2+)- and phospholipid-binding, and a variable N-terminal tail. A Ca(2+)-independent annexin 2-membrane association has been shown to be modulated by the presence of cholesterol in the membranes. Herein, the roles of the core and the N-terminal tail on the cholesterol-enhancement of annexin 2 membrane binding and aggregation were studied. The results show that (i) the cholesterol-mediated increase in membrane binding and in the Ca(2+) sensitivity for membrane aggregation were not modified by a N-terminal peptide (residues 15-26), and were conserved in mutants of the N-terminal end (S11 and S25 substitutions); (ii) cholesterol induced an increase in the Ca(2+)-dependent membrane binding and aggregation of the N-terminally truncated protein (Delta 1-29); and (iii) annexins 5 and 6, two proteins with unrelated N-terminal tails and homologous core domains showed a cholesterol-mediated enhancement of the Ca(2+)-dependent binding to membranes. These data indicate that the core domain is responsible for the cholesterol-mediated effects. A model for the cholesterol effect in membrane organisation, annexin binding and aggregation is discussed.
authors.affiliation: INSERM U332, Signalisation, Inflammation et Transformation Cellulaire, Institut Cochin de Génétique Moléculaire, 22 rue Méchain, Paris, 75014, France. ayala@cochin.inserm.fr
authors.forename: J
authors.initials: J
authors.lastname: Ayala-Sanmartin
mesh_terms: D017306:Annexin A2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017304:Annexin A5 / Q000378:metabolism; D017317:Annexin A6 / Q000378:metabolism; D017302:Annexins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008567:Membranes, Artificial; D008956:Models, Chemical; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D010743:Phospholipids / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects*; D017434:Protein Structure, Tertiary / Q000502:physiology
chemical_list: D017306:Annexin A2; D017304:Annexin A5; D017317:Annexin A6; D017302:Annexins; D008081:Liposomes; D008567:Membranes, Artificial; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D010743:Phospholipids; D002784:Cholesterol; D002118:Calcium