title: Two structural motifs within canonical EF-hand calcium-binding domains identify five different classes of calcium buffers and sensors.
abstract: Proteins with EF-hand calcium-binding motifs are essential for many cellular processes, but are also associated with cancer, autism, cardiac arrhythmias, and Alzheimer's, skeletal muscle and neuronal diseases. Functionally, all EF-hand proteins are divided into two groups: (1) calcium sensors, which function to translate the signal to various responses; and (2) calcium buffers, which control the level of free Ca2+ ions in the cytoplasm. The borderline between the two groups is not clear, and many proteins cannot be described as definitive buffers or sensors. Here, we describe two highly-conserved structural motifs found in all known different families of the EF-hand proteins. The two motifs provide a supporting scaffold for the DxDxDG calcium binding loop and contribute to the hydrophobic core of the EF hand domain. The motifs allow more precise identification of calcium buffers and calcium sensors. Based on the characteristics of the two motifs, we could classify individual EF-hand domains into five groups: (1) Open static; (2) Closed static; (3) Local dynamic; (4) Dynamic; and (5) Local static EF-hand domains.
authors.affiliation: Biochemistry, Department of Biosciences, Åbo Akademi University, Turku, Finland.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Denessiouk
authors.affiliation: Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Russia.
authors.forename: Sergei
authors.initials: S
authors.lastname: Permyakov
authors.affiliation: Biochemistry, Department of Biosciences, Åbo Akademi University, Turku, Finland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Denesyuk
authors.affiliation: Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Russia.
authors.forename: Eugene
authors.initials: E
authors.lastname: Permyakov
authors.affiliation: Biochemistry, Department of Biosciences, Åbo Akademi University, Turku, Finland.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D016000:Cluster Analysis; D030562:Databases, Protein; D020832:EF Hand Motifs; D057927:Hydrophobic and Hydrophilic Interactions; D054730:Protein Interaction Domains and Motifs; D016415:Sequence Alignment
chemical_list: D002135:Calcium-Binding Proteins; D002118:Calcium