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PDBsum entry 4mlw
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Metal binding protein
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PDB id
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4mlw
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DOI no:
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J Biol Chem
288:36160-36167
(2013)
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PubMed id:
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A highly conserved cysteine of neuronal calcium-sensing proteins controls cooperative binding of Ca2+ to recoverin.
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M.J.Ranaghan,
R.P.Kumar,
K.S.Chakrabarti,
V.Buosi,
D.Kern,
D.D.Oprian.
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ABSTRACT
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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.
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');
}
}
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