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Structural Basis for Calmodulin as a Dynamic Calcium Sensor
Journal article   Open access   Peer reviewed

Structural Basis for Calmodulin as a Dynamic Calcium Sensor

Miao Zhang, Cameron Abrams, Liping Wang, Anthony Gizzi, Liping He, Ruihe Lin, Yuan Chen, Patrick J Loll, John M Pascal and Ji-fang Zhang
Structure (London), v 20(5), pp 911-923
09 May 2012
PMID: 22579256
url
https://doi.org/10.1016/j.str.2012.03.019View
Published, Version of Record (VoR) Open

Abstract

Calmodulin is a prototypical and versatile Ca2+ sensor with EF hands as its high-affinity Ca2+ binding domains. Calmodulin is present in all eukaryotic cells, mediating Ca2+-dependent signaling. Upon binding Ca2+, calmodulin changes its conformation to form complexes with a diverse array of target proteins. Despite a wealth of knowledge on calmodulin, little is known on how target proteins regulate calmodulin's ability to bind Ca2+. Here, we take advantage of two splice variants of SK2 channels, which are activated by Ca2+-bound calmodulin but show different sensitivity to Ca2+ for their activation. Protein crystal structures and other experiments show that, depending on which SK2 splice variant it binds to, calmodulin adopts drastically different conformations with different affinities for Ca2+ at its C-lobe. Such target protein-induced conformational changes make calmodulin a dynamic Ca2+ sensor capable of responding to different Ca2+ concentrations in cellular Ca2+ signaling. ► We show structure of CaM-CaMBD2-b, a SK2 splice variant with reduced Ca2+ sensitivity ► Dramatic changes in the CaM structure in CaM-CaMBD2-b compared to CaM in CaM-CaMBD2-a ► Conformational changes at the CaM C-lobe result in its reduced affinity for Ca2+ ► Results demonstrate CaM alters its affinity for Ca2+ induced by the target proteins

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Collaboration types
Domestic collaboration
Web of Science research areas
Biochemistry & Molecular Biology
Biophysics
Cell Biology
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