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Publication Abstract from PubMed

SIGN-R1 is a principal receptor for microbial polysaccharides uptake and is responsible for C3 fixation via an unusual complement activation pathway on splenic marginal zone macrophages. In these macrophages, SIGN-R1 is also involved in anti-inflammatory activity of intravenous immunoglobulin by direct interaction with sialylated Fcs. The high-resolution crystal structures of SIGN-R1 carbohydrate recognition domain and its complexes with dextran sulfate or sialic acid, and of the sialylated Fc antibody provide insights into SIGN-R1's selective recognition of a-2,6-sialylated glycoproteins. Unexpectedly, an additional binding site has been found in the SIGNR1 carbohydrate recognition domain, structurally separate from the calcium-dependent carbohydrate-binding site. This secondary binding site could bind repetitive molecular patterns, as observed in microbial polysaccharides, in a calcium-independent manner. These two binding sites may allow SIGNR1 to simultaneously bind both immune glycoproteins and microbial polysaccharide components, accommodating SIGN-R1's ability to relate the recognition of microbes to the activation of the classical complement pathway.

Structural basis for selective recognition of endogenous and microbial polysaccharides by macrophage receptor SIGN-R1.,Silva-Martin N, Bartual SG, Ramirez-Aportela E, Chacon P, Park CG, Hermoso JA Structure. 2014 Nov 4;22(11):1595-606. PMID:25450767^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.