Siglec-1 Protein

Quality Statement:
Human Siglec-1, a 175-185 kDa glycoprotein, also known as sialoadhesin or CD169, selectively binds to 2,3-linked sialic acid residues. Siglec-1 is a type I transmembrane lectin with an amino-terminal V-set domain that interacts with sialylated ligands, preferentially N-acetylneuraminic acid (Neu5Ac) in an α2–3 linkage. Moreover, as Siglec-1 contains 16 Ig-like C2-type extracellular domains that separate the ligand-binding site from the cell surface, it is available for interaction with external ligands and not bound in cis to cell-surface molecules, which is what usually happens with shorter Siglecs that are also expressed by DCs. Siglec-1 is a receptor codified by an interferon-stimulated gene and is therefore potently upregulated on distinct human DCs, monocytes, and macrophages when these cells sense type I interferons (IFNs) such as IFNα.

Reference:
Crocker P.R., Paulson J.C., Varki A. Siglecs and their roles in the immune system. Nat. Rev. Immunol. 2007; 7:255–266. doi: 10.1038/nri2056.Hartnell A., Steel J., Turley H., Jones M., Jackson D.G., Crocker P.R. Characterization of human sialoadhesin, a sialic acid binding receptor expressed by resident and inflammatory macrophage populations. Blood. 2001; 97:288–296. doi: 10.1182/blo od. V97.1.288.Puryear W.B., Akiyama H., Geer S.D., Ramirez N.P., Yu X., Reinhard B.M., Gummuluru S. Interferon-inducible mechanism of dendritic cell-mediated HIV-1 dissemination is dependent on Siglec-1/CD169. PLoS Pathog. 2013; 9: e1003291. doi: 4.1371/journal. ppat.1003291.Rempel H., Calosing C., Sun B., Pulliam L. Sialoadhesin expressed on IFN-induced monocytes binds HIV-1 and enhances infectivity. PLoS ONE. 2008; 3: e1967. doi: 10.1371/journal.pone.0001967.