'''Calcium-bound D51A/E101D/F102W Triple Mutant of Beta Carp Parvalbumin'''
===Calcium-bound D51A/E101D/F102W Triple Mutant of Beta Carp Parvalbumin===
==Overview==
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BACKGROUND: The EF-hand family is a large set of Ca(2+)-binding proteins that contain characteristic helix-loop-helix binding motifs that are highly conserved in sequence. Members of this family include parvalbumin and many prominent regulatory proteins such as calmodulin and troponin C. EF-hand proteins are involved in a variety of physiological processes including cell-cycle regulation, second messenger production, muscle contraction, microtubule organization and vision. RESULTS: We have determined the structures of parvalbumin mutants designed to explore the role of the last coordinating residue of the Ca(2+)-binding loop. An E101D substitution has been made in the parvalbumin EF site. The substitution decreases the Ca(2+)-binding affinity 100-fold and increases the Mg(2+)-binding affinity 10-fold. Both the Ca(2+)- and Mg(2+)-bound structures have been determined, and a structural basis has been proposed for the metal-ion-binding properties. CONCLUSIONS: The E101D mutation does not affect the Mg(2+) coordination geometry of the binding loop, but it does pull the F helix 1.1 A towards the loop. The E101D-Ca(2+) structure reveals that this mutant cannot obtain the sevenfold coordination preferred by Ca(2+), presumably because of strain limits imposed by tertiary structure. Analysis of these results relative to previously reported structural information supports a model wherein the characteristics of the last coordinating residue and the plasticity of the Ca(2+)-binding loop delimit the allowable geometries for the coordinating sphere.
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==About this Structure==
==About this Structure==
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[[Category: Ef-hand protein]]
[[Category: Ef-hand protein]]
[[Category: Parvalbumin]]
[[Category: Parvalbumin]]
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Revision as of 15:34, 30 June 2008
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Metal-ion affinity and specificity in EF-hand proteins: coordination geometry and domain plasticity in parvalbumin., Cates MS, Berry MB, Ho EL, Li Q, Potter JD, Phillips GN Jr, Structure. 1999 Oct 15;7(10):1269-78. PMID:10545326
