1R1Z: The Crystal Structure Of The Carbohydrate Recognition Domain Of The Glycoprotein Sorting Receptor P58ERGIC-53 Reveals A Novel Metal Binding Site And Conformational Changes Associated With Calcium Ion Binding

p58/ERGIC-53 is a calcium-dependent animal lectin that acts as a cargo receptor, binding to a set of glycoproteins in the endoplasmic reticulum (ER) and transporting them to the Golgi complex. It is similar in structure to calcium-dependent leguminous lectins. We have determined the structure of the carbohydrate-recognition domain of p58/ERGIC-53 in its calcium-bound form. The structure reveals localized but large conformational changes in relation to the previously determined metal ion-free structure, mapping mostly to the ligand-binding site. It reveals the presence of two calcium ion-binding sites located 6A apart, one of which has no equivalent in the plant lectins. The second metal ion-binding site present in that class of lectins, binding Mn(2+), is absent from p58/ERGIC-53. The absence of a short loop in the ligand-binding site in this protein suggests that it has adapted to optimally bind the high-mannose Man(8)(GlcNAc)(2) glycan common to glycoproteins at the ER exit stage.
PDB ID: 1R1ZDownload
MMDB ID: 25759
PDB Deposition Date: 2003/9/25
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.4  Å
Source Organism:
Similar Structures:
Biological Unit for 1R1Z: monomeric; determined by author
Molecular Components in 1R1Z
Label Count Molecule
Protein (1 molecule)
Ergic-53 Protein(Gene symbol: Lman1)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB