title: Phosphoinositide specificity of and mechanism of lipid domain formation by annexin A2-p11 heterotetramer.
abstract: Annexin A2 is a phospholipid-binding protein that forms a heterotetramer (annexin II-p11 heterotetramer; A2t) with p11 (S100A10). It has been reported that annexin A2 is involved in binding to phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and in inducing membrane microdomain formation. To understand the mechanisms underlying these findings, we determined the membrane binding properties of annexin A2 wild type and mutants both as monomer and as A2t. Our results from surface plasmon resonance analysis showed that A2t and annexin A2 has modest selectivity for PtdIns(4,5)P2 over other phosphoinositides, which is conferred by conserved basic residues, including Lys279 and Lys281, on the convex surface of annexin A2. Fluorescence microscopy measurements using giant unilamellar vesicles showed that A2t of wild type, but not (K279A)2-(p11)2 or (K281A)2-(p11)2, specifically induced the formation of 1-microm-sized PtdIns(4,5)P2 clusters, which were stabilized by cholesterol. Collectively, these studies elucidate the structural determinant of the PtdIns(4,5)P2 selectivity of A2t and suggest that A2t may be involved in the regulation of PtdIns(4,5)P2 clustering in the cell.
authors.affiliation: Department of Chemistry, University of Illinois, Chicago, Illinois 60607-7061, USA.
authors.forename: Nikhil A
authors.initials: NA
authors.lastname: Gokhale
authors.forename: Alexandra
authors.initials: A
authors.lastname: Abraham
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Digman
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Wonhwa
authors.initials: W
authors.lastname: Cho
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017306:Annexin A2 / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry; D016000:Cluster Analysis; D018076:DNA, Complementary / Q000378:metabolism; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006801:Humans; D007700:Kinetics; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008239:Lysine / Q000737:chemistry; D021962:Membrane Microdomains; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry; D010716:Phosphatidylinositols / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D009418:S100 Proteins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance; D013997:Time Factors; D000099248:S100 Calcium Binding Protein A10
chemical_list: D017306:Annexin A2; D002784:Cholesterol; D018076:DNA, Complementary; D008055:Lipids; D008239:Lysine; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D009418:S100 Proteins; D000099248:S100 Calcium Binding Protein A10