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Many eukaryotic cellular and viral 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.

Molecular mechanics of calcium-myristoyl switches., Ames JB, Ishima R, Tanaka T, Gordon JI, Stryer L, Ikura M, Nature. 1997 Sep 11;389(6647):198-202. PMID:9296500

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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Categories: Bos taurus | Single protein | Ames, J B. | Gordon, J I. | Ikura, M. | Ishima, R. | Stryer, L. | Tanaka, T. | Calcium binding protein | Calcium-myristoyl switch