FEATURES

FAMILY

SIGLEC (sialic acid binding Ig-like lectin) family

DESCRIPTION

Also known as CD33_HUMAN, CD33, SIGLEC3. Sialic-acid-binding immunoglobulin-like lectin (Siglec) that plays a role in mediating cell-cell interactions and in maintaining immune cells in a resting state (PubMed:10611343, PubMed:15597323, PubMed:11320212). Preferentially recognizes and binds alpha-2, 3- and more avidly alpha-2, 6-linked sialic acid-bearing glycans (PubMed:7718872). Upon engagement of ligands such as C1q or syalylated glycoproteins, two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) located in CD33 cytoplasmic tail are phosphorylated by Src-like kinases such as LCK (PubMed:28325905, PubMed:10887109). These phosphorylations provide docking sites for the recruitment and activation of protein-tyrosine phosphatases PTPN6/SHP-1 and PTPN11/SHP-2 (PubMed:10556798, PubMed:10206955, PubMed:10887109). In turn, these phosphatases regulate downstream pathways through dephosphorylation of signaling molecules (PubMed:10206955, PubMed:10887109). One of the repressive effect of CD33 on monocyte activation requires phosphoinositide 3-kinase/PI3K (PubMed:15597323). Homodimer; disulfide-linked (PubMed:10887109). Interacts with PTPN6/SHP-1 and PTPN11/SHP-2 upon phosphorylation (PubMed:10556798, PubMed:10206955). Interacts with C1QA (via C-terminus); this interaction activates CD33 inhibitory motifs (PubMed:28325905).

EXTERNAL LINKS

CD33

Myeloid cell surface antigen CD33

CD33

Molecular Synopsis