Siglecs are sialic acid specific It ype lectins that belong to the immunoglobulin superfamily. Structurally, they are transmembrane proteins with an Nterminal Ig like Vset domain followed by varying numbers of Iglike C2set domains (1, 2). Mouse Siglec1, also known as sialoadhesin and CD169, is a 175 185kD glycoprotein that consists of a 1619 amino acid (aa) extracellular domain (ECD) with one Iglike Vset domain and 16 Iglike C2set domains, a 21 aa transmembrane segment , and a 35 aa cytoplasmic domain (3, 4). Within the ECD, mouse Siglec1 shares 73% and 83% aa sequence identity with human and rat Siglec1, respectively. Alternate splicing generates a soluble form of the ECD and a soluble isoform that is truncated following the first three Iglike domains (3). Siglec1 expression is restricted to lymphnode and spleen macrophages and some tissue macrophages (4). The adhesive function of Siglec1 is supported by the Nterminal Ig like domain which shows a selectivity for alpha2, 3linked sialic acid residues (46). Siglec1 binds a number of sialylated molecules including the mannose receptor, MGL1, MUC1, PSGL1, and different glycoforms of CD43 (710) . Its binding capacity can be masked by endogenous sialylated molecules (11, 12). The sialylated and sulfated Nlinked carbohydrates that modify Siglec1 itself are required for ligand binding (7,8). Siglec1 is expressed on dendritic cells following rhinovirus exposure, and these DC promote T cell anergy (13). It is also induced on circulating monocytes during systemic sclerosis and HI V1 infection (1416). Siglec1 can trap HI V1 particles for trans infection of permissive cells (15). Murine myeloma cell line, NS0-derived Mouse Siglec1 (Thr20 Arg1639) Accession NP_035556, IEGRMDP, Mouse IgG2a (Glu98 Lys330) N-terminal Sequence Analysis: Thr20 Structure: Disulfidelinked homodimer Predicted Molecular Mass: 201.7kD (monomer) SDS-PAGE: 190-205kD under reducing conditions Activity: Measured by the ability of the immobilized protein to support the adhesion of human red blood cells. Kelm, S. et al. (1994) Current Biology 4:965. The ED50 for this effect is typically ~0.6ug/ml. Endotoxin: 1.0 EU per 1ug of the protein by the LAL method. Applications: Suitable for use in ELISA. Other applications not tested. Recommended Dilution: Optimal dilutions to be determined by the researcher. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
