'''MANNOSE-BINDING PROTEIN-A MUTANT (QPDWGHV) COMPLEXED WITH N-ACETYL-D-GALACTOSAMINE'''
===MANNOSE-BINDING PROTEIN-A MUTANT (QPDWGHV) COMPLEXED WITH N-ACETYL-D-GALACTOSAMINE===
==Overview==
<!--
The mammalian hepatic asialoglycoprotein receptor, a member of the C-type animal lectin family, displays preferential binding to N-acetylgalactosamine compared with galactose. The structural basis for selective binding to N-acetylgalactosamine has been investigated. Regions of the carbohydrate-recognition domain of the receptor believed to be important in preferential binding to N-acetylgalactosamine have been inserted into the homologous carbohydrate-recognition domain of a mannose-binding protein mutant that was previously altered to bind galactose. Introduction of a single histidine residue corresponding to residue 256 of the hepatic asialoglycoprotein receptor was found to cause a 14-fold increase in the relative affinity for N-acetylgalactosamine compared with galactose. The relative ability of various acyl derivatives of galactosamine to compete for binding to this modified carbohydrate-recognition domain suggest that it is a good model for the natural N-acetylgalactosamine binding site of the asialoglycoprotein receptor. Crystallographic analysis of this mutant carbohydrate-recognition domain in complex with N-acetylgalactosamine reveals a direct interaction between the inserted histidine residue and the methyl group of the N-acetyl substituent of the sugar. Evidence for the role of the side chain at position 208 of the receptor in positioning this key histidine residue was obtained from structural analysis and mutagenesis experiments. The corresponding serine residue in the modified carbohydrate-recognition domain of mannose-binding protein forms a hydrogen bond to the imidazole side chain. When this serine residue is changed to valine, loss in selectivity for N-acetylgalactosamine is observed. The structure of this mutant reveals that the beta-branched valine side chain interacts directly with the histidine side chain, resulting in an altered imidazole ring orientation.
The line below this paragraph, {{ABSTRACT_PUBMED_9677372}}, adds the Publication Abstract to the page
(as it appears on PubMed at http://www.pubmed.gov), where 9677372 is the PubMed ID number.
-->
{{ABSTRACT_PUBMED_9677372}}
==About this Structure==
==About this Structure==
Line 27:
Line 31:
[[Category: Calcium-binding protein]]
[[Category: Calcium-binding protein]]
[[Category: Lectin]]
[[Category: Lectin]]
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:20:32 2008''
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 18:50:07 2008''
Revision as of 18:50, 30 June 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
