In the endoplasmic reticulum, calreticulin acts as a chaperone and a
Ca2+-signalling protein. At the cell surface, it mediates
numerous important biological effects. The crystal structure of the human
calreticulin globular domain was solved at 1.55 Å resolution. Interactions
of the flexible N-terminal extension with the edge of the lectin site are
consistently observed, revealing a hitherto unidentified peptide-binding site. A
calreticulin molecular zipper, observed in all crystal lattices, could further
extend this site by creating a binding cavity lined by hydrophobic residues.
These data thus provide a first structural insight into the lectin-independent
binding properties of calreticulin and suggest new working hypotheses, including
that of a multi-molecular mechanism.
Publisher: Public Library of Science
Date Published: 15-March-2011
Author(s): Chouquet A., Païdassi H., Ling W., Frachet P., Houen G., Arlaud G., Gaboriaud C.