1egg
From Proteopedia
STRUCTURE OF A C-TYPE CARBOHYDRATE-RECOGNITION DOMAIN (CRD-4) FROM THE MACROPHAGE MANNOSE RECEPTOR
Overview
The mannose receptor of macrophages and liver endothelium mediates clearance of pathogenic organisms and potentially harmful glycoconjugates. The extracellular portion of the receptor includes eight C-type carbohydrate recognition domains (CRDs), of which one, CRD-4, shows detectable binding to monosaccharide ligands. We have determined the crystal structure of CRD-4. Although the basic C-type lectin fold is preserved, a loop extends away from the core of the domain to form a domain-swapped dimer in the crystal. Of the two Ca(2+) sites, only the principal site known to mediate carbohydrate binding in other C-type lectins is occupied. This site is altered in a way that makes sugar binding impossible in the mode observed in other C-type lectins. The structure is likely to represent an endosomal form of the domain formed when Ca(2+) is lost from the auxiliary calcium site. The structure suggests a mechanism for endosomal ligand release in which the auxiliary calcium site serves as a pH sensor. Acid pH-induced removal of this Ca(2+) results in conformational rearrangements of the receptor, rendering it unable to bind carbohydrate ligands.
About this Structure
1EGG is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structure of a C-type carbohydrate recognition domain from the macrophage mannose receptor., Feinberg H, Park-Snyder S, Kolatkar AR, Heise CT, Taylor ME, Weis WI, J Biol Chem. 2000 Jul 14;275(28):21539-48. PMID:10779515 Page seeded by OCA on Fri May 2 15:04:20 2008
