This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1fih
From Proteopedia
|
N-ACETYLGALACTOSAMINE BINDING MUTANT OF MANNOSE-BINDING PROTEIN A (QPDWG-HDRPY), COMPLEX WITH N-ACETYLGALACTOSAMINE
Overview
Efficient release of ligands from the Ca(2+)-dependent, carbohydrate-recognition domain (CRD) of the hepatic asialoglycoprotein, receptor at endosomal pH requires a small set of conserved amino acids, that includes a critical histidine residue. When these residues are, incorporated at corresponding positions in an homologous galactose-binding, derivative of serum mannose-binding protein, the pH dependence of ligand, binding becomes more like that of the receptor. The modified CRD displays, 40-fold preferential binding to N-acetylgalactosamine compared with, galactose, making it a good functional mimic of the asialoglycoprotein, receptor. In the crystal structure of the modified CRD bound to, N-acetylgalactosamine, the histidine (His(202)) contacts the 2-acetamido, methyl group and also participates in a network of interactions involving, Asp(212), Arg(216), and Tyr(218) that positions a water molecule in a, hydrogen bond with the sugar amide group. These interactions appear to, produce the preference for N-acetylgalactosamine over galactose and are, also likely to influence the pK(a) of His(202). Protonation of His(202), would disrupt its interaction with an asparagine that serves as a ligand, for Ca(2+) and sugar. The structure of the modified CRD without sugar, displays several different conformations that may represent structures of, intermediates in the release of Ca(2+) and sugar ligands caused by, protonation of His(202).
About this Structure
1FIH is a Single protein structure of sequence from Rattus norvegicus with NGA, CA and CL as ligands. Full crystallographic information is available from OCA.
Reference
Mechanism of pH-dependent N-acetylgalactosamine binding by a functional mimic of the hepatocyte asialoglycoprotein receptor., Feinberg H, Torgersen D, Drickamer K, Weis WI, J Biol Chem. 2000 Nov 10;275(45):35176-84. PMID:10931846
Page seeded by OCA on Tue Nov 20 14:56:58 2007
Categories: Rattus norvegicus | Single protein | Drickamer, K. | Feinberg, H. | Torgerson, D. | Weis, W.I. | CA | CL | NGA | C-type lectin | Calcium-binding protein | Lectin
