title: Diversity of conformational states and changes within the EF-hand protein superfamily.
abstract: The EF-hand motif, which assumes a helix-loop-helix structure normally responsible for Ca2+ binding, is found in a large number of functionally diverse Ca2+ binding proteins collectively known as the EF-hand protein superfamily. In many superfamily members, Ca2+ binding induces a conformational change in the EF-hand motif, leading to the activation or inactivation of target proteins. In calmodulin and troponin C, this is described as a change from the closed conformational state in the absence of Ca2+ to the open conformational state in its presence. It is now clear from structures of other EF-hand proteins that this "closed-to-open" conformational transition is not the sole model for EF-hand protein structural response to Ca2+. More complex modes of conformational change are observed in EF-hand proteins that interact with a covalently attached acyl group (e.g., recoverin) and in those that dimerize (e.g., S100B, calpain). In fact, EF-hand proteins display a multitude of unique conformational states, together constituting a conformational continuum. Using a quantitative 3D approach termed vector geometry mapping (VGM), we discuss this tertiary structural diversity of EF-hand proteins and its correlation with target recognition.
authors.affiliation: Division of Molecular and Structural Biology, Ontario Cancer Institute, Toronto, Canada.
authors.forename: K L
authors.initials: KL
authors.lastname: Yap
authors.forename: J B
authors.initials: JB
authors.lastname: Ames
authors.forename: M B
authors.initials: MB
authors.lastname: Swindells
authors.forename: M
authors.initials: M
authors.lastname: Ikura
mesh_terms: D020816:Amino Acid Motifs; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002147:Calmodulin / Q000737:chemistry; D018257:Helix-Loop-Helix Motifs; D008968:Molecular Conformation; D011487:Protein Conformation; D019209:Troponin C / Q000737:chemistry
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D019209:Troponin C