Database accession: MF7000585
Name: Ca2+-bound Calcyclin
PDB ID: 1jwd
Experimental method: NMR
Assembly: Homodimer
Source organism: Oryctolagus cuniculus
Primary publication of the structure:
Mäler L, Sastry M, Chazin WJ
A structural basis for S100 protein specificity derived from comparative analysis of apo and Ca(2+)-calcyclin.
(2002) J. Mol. Biol. 317: 279-90
PMID: 11902843
Abstract:
Calcyclin is a homodimeric protein belonging to the S100 subfamily of EF-hand Ca(2+)-binding proteins, which function in Ca(2+) signal transduction processes. A refined high-resolution solution structure of Ca(2+)-bound rabbit calcyclin has been determined by heteronuclear solution NMR. In order to understand the Ca(2+)-induced structural changes in S100 proteins, in-depth comparative structural analyses were used to compare the apo and Ca(2+)-bound states of calcyclin, the closely related S100B, and the prototypical Ca(2+)-sensor protein calmodulin. Upon Ca(2+) binding, the position and orientation of helix III in the second EF-hand is altered, whereas the rest of the protein, including the dimer interface, remains virtually unchanged. This Ca(2+)-induced structural change is much less drastic than the "opening" of the globular EF-hand domains that occurs in classical Ca(2+) sensors, such as calmodulin. Using homology models of calcyclin based on S100B, a binding site in calcyclin has been proposed for the N-terminal domain of annexin XI and the C-terminal domain of the neuronal calcyclin-binding protein. The structural basis for the specificity of S100 proteins is discussed in terms of the variation in sequence of critical contact residues in the common S100 target-binding site.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
calcium ion binding calcium ion binding
calcium-dependent protein binding calcium-dependent protein binding
S100 protein binding S100 protein binding
Biological process: not assigned
Cellular component:
collagen-containing extracellular matrix collagen-containing extracellular matrix
cytoplasmic side of plasma membrane cytoplasmic side of plasma membrane
cytosol cytosol
extracellular space extracellular space
nuclear envelope nuclear envelope
perinuclear region of cytoplasm perinuclear region of cytoplasm
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: Protein S100-A6
Source organism: Oryctolagus cuniculus
Length: 90 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMASPLDQAIGLLIGIFHKYSGKEGDKHTLSKKELKELIQKELTIGSKLQDAEIVKLMDDLDRNKDQEVNFQEYITFLGALAMIYNEALKG
UniProtKB AC: P30801 (positions: 1-90)
Coverage: 100%
Name: Protein S100-A6
Source organism: Oryctolagus cuniculus
Length: 90 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMASPLDQAIGLLIGIFHKYSGKEGDKHTLSKKELKELIQKELTIGSKLQDAEIVKLMDDLDRNKDQEVNFQEYITFLGALAMIYNEALKG
UniProtKB AC: P30801 (positions: 1-90)
Coverage: 100%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: S-100/ICaBP type EF hand dimer
Evidence level: Direct evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
GuHCl-induced denaturation of the S100B protein dimer showed that it follows a two-state unfolding/refolding process (PMID:11888280). Other S100 proteins also showed two-state unfolding, no folded monomers were observed (PMID:18346834, PMID:18706914). The dimer has a globular and compact structure with the four helices in each subunit aligning to form a unicornate-type four-helix bundle (PMID:11790100). The hydrophobic core extends through the dimer interface.
Chain A:
N/A
Chain B:
N/A
Surface and contacts features:
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). Download the CIF file (.cif)
Download this entry's XML file (.xml)
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