1gjy
From Proteopedia
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THE X-RAY STRUCTURE OF THE SORCIN CALCIUM BINDING DOMAIN (SCBD) PROVIDES INSIGHT INTO THE PHOSPHORYLATION AND CALCIUM DEPENDENT PROCESSESS
Overview
Sorcin is a 21.6 kDa calcium binding protein, expressed in a number of, mammalian tissues that belongs to the small, recently identified, penta-EF-hand (PEF) family. Like all members of this family, sorcin, undergoes a Ca2+-dependent translocation from cytosol to membranes where, it binds to target proteins. For sorcin, the targets differ in different, tissues, indicating that it takes part in a number of Ca2+-regulated, processes. The sorcin monomer is organized in two domains like in all PEF, proteins: a flexible, hydrophobic, glycine-rich N-terminal region and a, calcium binding C-terminal domain. In vitro, the PEF proteins are dimeric, in their Ca2+-free form, but have a marked tendency to precipitate when, bound to calcium. Stabilization of the dimeric structure is achieved by, pairing of the uneven EF-hand, EF5. Sorcin can also form tetramers at acid, pH.The sorcin calcium binding domain (SCBD, residues 33-198) expressed in, Escherichia coli was crystallized in the Ca2+-free form. The structure was, solved by molecular replacement and was refined to 2.2 A with a, crystallographic R-factor of 22.4 %. Interestingly, the asymmetric unit, contains two dimers.The structure of the SCBD leads to a model that, explains the solution properties and describes the Ca2+-induced, conformational changes. Phosphorylation studies show that the N-terminal, domain hinders phosphorylation of SCBD, i.e. the rate of phosphorylation, increased twofold in the absence of the N-terminal region. In addition, previous fluorescence studies indicated that hydrophobic residues are, exposed to solvent upon Ca2+ binding to full-length sorcin. The model, accounts for these data by proposing that Ca2+ binding weakens the, interactions between the two domains and leads to their reorientation, which exposes hydrophobic regions facilitating the Ca2+-dependent binding, to target proteins at or near membranes.
About this Structure
1GJY is a Single protein structure of sequence from Cricetulus longicaudatus with as ligand. Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
The crystal structure of the sorcin calcium binding domain provides a model of Ca2+-dependent processes in the full-length protein., Ilari A, Johnson KA, Nastopoulos V, Verzili D, Zamparelli C, Colotti G, Tsernoglou D, Chiancone E, J Mol Biol. 2002 Mar 29;317(3):447-58. PMID:11922676
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