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Publication Abstract from PubMed

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.

The crystal structure of the carbohydrate-recognition domain of the glycoprotein sorting receptor p58/ERGIC-53 reveals an unpredicted metal-binding site and conformational changes associated with calcium ion binding.,Velloso LM, Svensson K, Pettersson RF, Lindqvist Y J Mol Biol. 2003 Dec 12;334(5):845-51. PMID:14643651^[1]

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