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Publication Abstract from PubMed

Recoverin, a 23-kDa Ca(2+)-binding protein of the neuronal calcium sensing (NCS) family, inhibits rhodopsin kinase, a Ser/Thr kinase responsible for termination of photoactivated rhodopsin in rod photoreceptor cells. Recoverin has two functional EF hands and a myristoylated N terminus. The myristoyl chain imparts cooperativity to the Ca(2+)-binding sites through an allosteric mechanism involving a conformational equilibrium between R and T states of the protein. Ca(2+) binds preferentially to the R state; the myristoyl chain binds preferentially to the T state. In the absence of myristoylation, the R state predominates, and consequently, binding of Ca(2+) to the non-myristoylated protein is not cooperative. We show here that a mutation, C39A, of a highly conserved Cys residue among NCS proteins, increases the apparent cooperativity for binding of Ca(2+) to non-myristoylated recoverin. The binding data can be explained by an effect on the T/R equilibrium to favor the T state without affecting the intrinsic binding constants for the two Ca(2+) sites.

A Highly Conserved Cysteine of Neuronal Calcium-sensing Proteins Controls Cooperative Binding of Ca2+ to Recoverin.,Ranaghan MJ, Kumar RP, Chakrabarti KS, Buosi V, Kern D, Oprian DD J Biol Chem. 2013 Dec 13;288(50):36160-7. doi: 10.1074/jbc.M113.524355. Epub 2013, Nov 4. PMID:24189072^[3]

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