1JUO

Crystal Structure of Calcium-free Human Sorcin: A Member of the Penta-EF-Hand Protein Family

Summary for 1JUO

• Entry DOI: 10.2210/pdb1juo/pdb
• Descriptor: sorcin (2 entities in total)
• Functional Keywords: calcium-binding proteins, penta-ef-hand, pef, metal transport
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: P30626
• Total number of polymer chains: 2
• Total formula weight: 43390.67

Authors

Xie, X. (deposition date: 2001-08-24, release date: 2002-01-30, Last modification date: 2024-02-07)

Primary citation

Xie, X.,Dwyer, M.D.,Swenson, L.,Parker, M.H.,Botfield, M.C.
Crystal structure of calcium-free human sorcin: a member of the penta-EF-hand protein family.
Protein Sci., 10:2419-2425, 2001

PubMed Abstract: Sorcin is a 22 kD calcium-binding protein that is found in a wide variety of cell types, such as heart, muscle, brain and adrenal medulla. It belongs to the penta-EF-hand (PEF) protein family, which contains five EF-hand motifs that associate with membranes in a calcium-dependent manner. Prototypic members of this family are the calcium-binding domains of calpain, such as calpain dVI. Full-length human sorcin has been crystallized in the absence of calcium and the structure determined at 2.2 A resolution. Apart from an extended N-terminal portion, the sorcin molecule has a globular shape. The C-terminal domain is predominantly alpha-helical, containing eight alpha-helices and connecting loops incorporating five EF hands. Sorcin forms dimers through the association of the unpaired EF5, confirming this as the mode of association in the dimerization of PEF proteins. Comparison with calpain dVI reveals that the general folds of the individual EF-hand motifs are conserved, especially that of EF1, the novel EF-hand motif characteristic of the family. Detailed structural comparisons of sorcin with other members of PEF indicate that the EF-hand pair EF1-EF2 is likely to correspond to the two physiologically relevant calcium-binding sites and that the calcium-induced conformational change may be modest and localized within this pair of EF-hands. Overall, the results derived from the structural observations support the view that, in sorcin, calcium signaling takes place through the first pair of EF-hands.

PubMed: 11714909
DOI: 10.1110/ps.ps.36701

Experimental method

X-RAY DIFFRACTION (2.2 Å)