SIGLEC1 encodes a member of the immunoglobulin superfamily. The encoded protein is a lectin-like adhesion molecule that binds glycoconjugate ligands on cell surfaces in a sialic acid-dependent manner. It is a type I transmembrane protein expressed only by a subpopulation of macrophages and is involved in mediating cell-cell interactions. Alternative splicing produces a transcript variant encoding an isoform that is soluble rather than membrane-bound; however, the full-length nature of this variant has not been determined. [provided by RefSeq]. 
Acts as an endocytic receptor mediating clathrin dependent endocytosis. Macrophage-restricted adhesion molecule that mediates sialic-acid dependent binding to lymphocytes, including granulocytes, monocytes, natural killer cells, B-cells and CD8 T-cells. Preferentially binds to alpha-2,3-linked sialic acid (By similarity). Binds to SPN/CD43 on T-cells (By similarity). May play a role in hemopoiesis.