title: Role of calcium-binding sites in calcium-dependent membrane association of annexin A4.
abstract: Annexin A4 (Anx4) is a cytosolic calcium-binding protein with four repeat domains, each containing one calcium-binding site (CBS). The protein interacts with the phospholipid membrane through the CBS-coordinated calcium ion, although the role of each CBS in the calcium-dependent association is unclear. To determine the role of each CBS, 15 CBS-abolished variants were produced in various combinations by substitution of a calcium-liganding residue on each CBS by Ala. Various mutant combinations produced different influences on calcium-dependent membrane-binding behavior and on the sodium-dependent dissociation of membrane-bound Anx4. Our data suggest the interaction of Anx4 with the lipid membrane consists of strong and weak interactions. CBSs I and IV mediate formation of strong interactions, while CBSs II and III are important for weak interactions. We also suggest Anx4 binds the lipid membrane through CBSs I and IV in the cytoplasmic fluids.
authors: a Department of Food Science and Nutrition , School of Human Environmental Sciences, Mukogawa Women's University , Nishinomiya , Japan.
authors: Yasuhiro
authors: Y
authors: Arii
authors: Kohei
authors: K
authors: Butsusihta
authors: Shin-Ichi
authors: S
authors: Fukuoka
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D017314:Annexin A4 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats
chemical_list: D017314:Annexin A4; D002118:Calcium
keywords: annexin; calcium-binding protein; lipid-binding protein; metal ion–protein interaction