1egg
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(New page: 200px<br /> <applet load="1egg" size="450" color="white" frame="true" align="right" spinBox="true" caption="1egg, resolution 2.30Å" /> '''STRUCTURE OF A C-TY...)
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Revision as of 14:36, 12 November 2007
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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 with CA as ligand. 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
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