Structure of calmodulin refined at 2.2 Å resolution

doi:10.1016/0022-2836(88)90608-0

Journal of Molecular Biology

Volume 204, Issue 1, 5 November 1988, Pages 191-204

https://doi.org/10.1016/0022-2836(88)90608-0 Get rights and content

Abstract

The crystal structure of mammalian calmodulin has been refined at 2.2 Å (1 Å = 0.1 nm) resolution using a restrained least-squares method. The final crystallographic R-factor, based on 6685 reflections in the range 2.2 Å ≤ d ≤ 5.0 Å with intensities exceeding 2.5 σ, is 0.175. Bond lengths and bond angles in the molecule have root-mean-square deviations from ideal values of 0.016 Å and 1.7 °, respectively. The refined model includes residues 5 to 147, four Ca²⁺ and 69 water molecules per molecule of calmodulin. The electron density for residues 1 to 4 and 148 is poorly defined, and they are not included in the model.

The molecule is shaped somewhat like a dumbbell, with an overall length of 65 Å; the two lobes are connected by a seven-turn α-helix. Prominent secondary structural features include seven α-helices, four Ca²⁺-binding loops, and two short, double-stranded antiparallel beta-sheets between pairs of adjacent Ca²⁺-binding loops. The four Ca²⁺-binding domains in calmodulin have a typical EF hand conformation (helix-loop-helix) and are similar to those described in other Ca²⁺-binding proteins. The X-ray structure determination of calmodulin shows a large hydrophobic cleft in each half of the molecule. These hydrophobic regions probably represent the sites of interaction with many of the pharmacological agents known to bind to calmodulin.

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^☆: Many of the illustrations used in this paper were composed using programs developed by Dr Mike Carson. This work was supported by National Institutes of Health grants GM-29427, CA-13148 and DE-02670.

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Journal of Molecular Biology

Structure of calmodulin refined at 2.2 Å resolution☆

Abstract

Progr. Biophys. Mol. Biol

Biochem. Biophys. Res. Commun

Methods Enzymol

J. Biol. Chem

Arch. Biochem. Biophys

J. Biol. Chem

J. Biol. Chem

Advan. Protein Chem

J. Biol. Chem

J. Biol. Chem

J. Biol. Chem

J. Mol. Biol

J. Mol. Biol

J. Biol. Chem

J. Biol. Chem

J. Biol. Chem

FEBS Letters