Macrophage-restricted adhesion molecule that mediates sialic-acid dependent binding to lymphocytes, including granulocytes, monocytes, natural killer cells, B-cells and CD8 T-cells. Plays a crucial role in limiting bacterial dissemination by engaging sialylated bacteria to promote effective phagocytosis and antigen presentation for the adaptive immune response (, ). Mediates the uptake of various enveloped viruses via sialic acid recognition and subsequently induces the formation of intracellular compartments filled with virions (VCCs). In turn, enhances macrophage-to-T-cell transmission of several viruses including HIV-1 or SARS-CoV-2 (, ). Acts as an endocytic receptor mediating clathrin dependent endocytosis. Preferentially binds to alpha-2,3-linked sialic acid . Binds to SPN/CD43 on T-cells (By similarity). May play a role in hemopoiesis. Plays a role in the inhibition of antiviral innate immune by promoting TBK1 degradation via TYROBP and TRIM27-mediated ubiquitination .
(Microbial infection) Facilitates viral cytoplasmic entry into activated dendritic cells via recognition of sialylated gangliosides pesent on viral membrane.
Subcellular locations: Cell membrane
Subcellular locations: Secreted
Expressed by macrophages in various tissues. High levels are found in spleen, lymph node, perivascular macrophages in brain and lower levels in bone marrow, liver Kupffer cells and lamina propria of colon and lung. Also expressed by inflammatory macrophages in rheumatoid arthritis.