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Konstantin E. Komolov, Dimitri V. Zinchenko, Valeriya A. Churumova, Svetlana A. Vaganova, Oliver H. Weiergräber, Ivan I. Senin, Pavel P. Philippov, Karl-Wilhelm Koch

One of the Ca²⁺ binding sites of recoverin exclusively controls interaction with rhodopsin kinase

Keywords: calcium signalling, neuronal calcium sensor, phototransduction

Recoverin is a neuronal calcium sensor protein that controls the activity of rhodopsin kinase in a Ca²⁺-dependent manner. Mutations in the EF-hand Ca²⁺ binding sites are valuable tools for investigating the functional properties of recoverin. In the recoverin mutant E121Q (Rec^E121Q) the high-affinity Ca²⁺ binding site is disabled. The non-myristoylated form of Rec^E121Q binds one Ca²⁺ via its second Ca²⁺-binding site (EF-hand 2), whereas the myristoylated variant does not bind Ca²⁺ at all. Binding of Ca²⁺ to non-myristoylated Rec^E121Q apparently triggers exposure of apolar side chains, allowing for association with hydrophobic matrices. Likewise, an interaction surface for the recoverin target rhodopsin kinase is constituted upon Ca²⁺ binding to the non-acylated mutant. Structural changes resulting from Ca²⁺-occupation of EF-hand 2 in myristoylated and non-myristoylated recoverin variants are discussed in terms of critical conditions required for biological activity.

Biological Chemistry, Walter de Gruyter

Print ISSN: 1431-6730
Volume: 386, 03/2005
Pages: 285 - 289

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