Molecular mechanics of calcium-myristoyl switches

James B. Ames, Rieko Ishima, Toshiyuki Tanaka, Jeffrey I. Gordon, Lubert Stryer, Mitsuhiko Ikura

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Many eukaryotic cellular and vital proteins have a covalently attached myristoyl group at the amino terminus. One such protein is recoverin, a calcium sensor in retinal rod cells, which controls the lifetime of photoexcited rhodopsin by inhibiting rhodopsin kinase. Recoverin has a relative molecular mass of 23,000 (M(r) 23K), and contains an amino-terminal myristoyl group (or related acyl group) and four EF hands. The binding of two Ca2+ ions to recoverin leads to its translocation from the cytosol to the disc membrane. In the Ca2+-free state, the myristoyl group is sequestered in a deep hydrophobic box, where it is clamped by multiple residues contributed by three of the EF hands. We have used nuclear magnetic resonance to show that Ca2+ induces the unclamping and extrusion of the myristoyl group, enabling it to interact with a lipid bilayer membrane. The transition is also accompanied by a 45-degree rotation of the amino-terminal domain relative to the carboxy-terminal domain, and many hydrophobic residues are exposed. The conservation of the myristoyl binding site and two swivels in recoverin homologues from yeast to humans indicates that calcium-myristoyl switches are ancient devices for controlling calcium-sensitive processes.

Original languageEnglish
Pages (from-to)198-202
Number of pages5
Issue number6647
StatePublished - Oct 2 1997

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    Ames, J. B., Ishima, R., Tanaka, T., Gordon, J. I., Stryer, L., & Ikura, M. (1997). Molecular mechanics of calcium-myristoyl switches. Nature, 389(6647), 198-202.