2KYF: solution structure of calcium-bound CPV3

Birds express two beta-parvalbumin isoforms, parvalbumin 3 and avian thymic hormone (ATH). Parvalbumin 3 from chicken (CPV3) is identical to rat beta-parvalbumin (beta-PV) at 75 of 108 residues. CPV3 displays intermediate Ca(2+) affinity--higher than that of rat beta-parvalbumin, but lower than that of ATH. As in rat beta-PV, the attenuation of affinity is associated primarily with the CD site (residues 41-70), rather than the EF site (residues 80-108). Structural data for rat alpha- and beta-parvalbumins suggest that divalent ion affinity is correlated with the similarity of the unliganded and Ca(2+)-bound conformations. We herein present a comparison of the solution structures of Ca(2+)-free and Ca(2+)-bound CPV3. Although the structures are generally similar, the conformations of residues 47 to 50 differ markedly in the two protein forms. These residues are located in the C helix, proximal to the CD binding loop. In response to Ca(2+) removal, F47 experiences much greater solvent accessibility. The side-chain of R48 assumes a position between the C and D helices, adjacent to R69. Significantly, I49 adopts an interior position in the unliganded protein that allows association with the side-chain of L50. Concomitantly, the realignment of F66 and F70 facilitates their interaction with I49 and reduces their contact with residues in the N-terminal AB domain. This reorganization of the hydrophobic core, although less profound, is nevertheless reminiscent of that observed in rat beta-PV. The results lend further support to the idea that Ca(2+) affinity correlates with the structural similarity of the apo- and bound parvalbumin conformations.
PDB ID: 2KYFDownload
MMDB ID: 89622
PDB Deposition Date: 2010/5/25
Updated in MMDB: 2018/05
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Biological Unit for 2KYF: monomeric; determined by author
Molecular Components in 2KYF
Label Count Molecule
Protein (1 molecule)
Parvalbumin, Thymic Cpv3(Gene symbol: OCM)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

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