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Publication Abstract from PubMed

Due to its favorable spectroscopic properties, Cd2+ is frequently used as a probe of Ca2+ sites in proteins. We investigate the ability of Cd2+ to act as a structural and functional surrogate of Ca2+ in protein-membrane interactions. C2 domain from protein kinase Calpha (C2alpha) was chosen as a paradigm for the Ca2+-dependent phosphatidylserine-binding peripheral membrane domains. We identified the Cd2+-binding sites of C2alpha using NMR spectroscopy, determined the 1.6 A crystal structure of Cd2+-bound C2alpha, and characterized metal-ion-dependent interactions between C2alpha and phospholipid membranes using fluorescence spectroscopy and ultracentrifugation experiments. We show that Cd2+ forms a tight complex with the membrane-binding loops of C2alpha but is unable to support its membrane-binding function. This is in sharp contrast with Pb2+, which is almost as effective as Ca2+ in driving the C2alpha-membrane association process. Our results provide the first direct evidence for the specific role of divalent metal ions in mediating protein-membrane interactions, have important implications for metal substitution studies in proteins, and illustrate the potential diversity of functional responses caused by toxic metal ions.

Cd as a Ca Surrogate in Protein-Membrane Interactions: Isostructural but Not Isofunctional.,Morales KA, Yang Y, Long Z, Li P, Taylor AB, Hart PJ, Igumenova TI J Am Chem Soc. 2013 Aug 21. PMID:23937054^[1]

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