2zg3

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spinqualitylabelsall models 2zg3, resolution 3.0Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of Two N-terminal Domains of Native Siglec-5 in Complex with 3'-Sialyllactose

Overview

Sialic acid (Sia) Ig-like binding lectins are important mediators of recognition and signaling events among myeloid cells. To investigate the molecular mechanism underlying sialic acid Ig-like lectin (Siglec) functions, we determined the crystal structure of the two N-terminal extracellular domains of human myeloid cell inhibitory receptor Siglec-5 (CD170) and its complexes with two sialylated carbohydrates. The native structure revealed an unusual conformation of the CC' ligand specificity loop and a unique interdomain disulfide bond. The alpha(2,3)- and alpha(2,6)-sialyllactose complexed structures showed a conserved Sia recognition motif that involves both Arg124 and a portion of the G-strand in the V-set domain forming beta-sheet-like hydrogen bonds with the glycerol side chain of the Sia. Only few protein contacts to the subterminal sugars are observed and mediated by the highly variable GG' linker and CC' loop. These structural observations, in conjunction with surface plasmon resonance binding assays, provide mechanistic insights into linkage-dependent Siglec carbohydrate recognition and suggest that Siglec-5 and other CD33-related Siglec receptors are more promiscuous in sialoglycan recognition than previously understood.

About this Structure

2ZG3 is a Single protein structure of sequence from Homo sapiens. Known structural/functional Sites: , and . Full crystallographic information is available from OCA.

Reference

Structural implications of Siglec-5-mediated sialoglycan recognition., Zhuravleva MA, Trandem K, Sun PD, J Mol Biol. 2008 Jan 11;375(2):437-47. Epub 2007 Oct 11. PMID:18022638

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