Publication Details (including relevant citation information):
Ranaghan, M. J., Kumar, R. P., Chakrabarti, K. S., Buosi, V., Kern, D., and Oprian, D. D. (2013) J. Biol. Chem. 288 (50): 36160-7.
Recoverin, a 23-kDa Ca2+-binding protein of the neuronal calcium sensing (NCS) family, inhibits rhodopsin kinase, a Ser/ Thr kinase responsible for termination of photoactivated rho- dopsin in rod photoreceptor cells. Recoverin has two functional EF hands and a myristoylated N terminus. The myristoyl chain imparts cooperativity to the Ca2+-binding sites through an allosteric mechanism involving a conformational equilibrium between R and T states of the protein. Ca2+ binds preferentially to the R state; the myristoyl chain binds preferentially to the T state. In the absence of myristoylation, the R state predomi- nates, and consequently, binding of Ca2+ 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 Ca2+ 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 Ca2+ sites.
Address (URL): http://dx.doi.org/10.1074/jbc.M113.524355