SIGLEC1

Function

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 (PubMed:12940982, PubMed:33489013). Mediates the uptake of various enveloped viruses via sialic acid recognition and subsequently induces the formation of intracellular compartments filled with virions (VCCs) (PubMed:28129379). In turn, enhances macrophage-to-T-cell transmission of several viruses including HIV-1 or SARS-CoV-2 (PubMed:28129379, PubMed:34782760). Acts as an endocytic receptor mediating clathrin dependent endocytosis. Preferentially binds to alpha-2,3-linked sialic acid (PubMed:12940982). 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 (PubMed:26358190).

(Microbial infection) Facilitates viral cytoplasmic entry into activated dendritic cells via recognition of sialylated gangliosides pesent on viral membrane.

Sequence Similarities

Belongs to the immunoglobulin superfamily. SIGLEC (sialic acid binding Ig-like lectin) family.

Tissue Specificity

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.

Cellular localization

• Isoform 1
• Cell membrane
• Single-pass type I membrane protein
• Isoform 2
• Secreted

Alternative names

CD169, SN, SIGLEC1, Sialoadhesin, Sialic acid-binding Ig-like lectin 1, Siglec-1

Database links

swissprot:Q9BZZ2 omim:600751 entrezGene:6614

Other research areas

• Immuno-oncology