Zurück zu Ihrem Suchergebnis

Beschreibung

Myeloid cell surface antigen CD33 (UniProt: P20138, also known as Sialic acid-binding Ig-like lectin 3, Siglec-3, gp67, CD33) is encoded by the CD33 (also known as SIGLEC3) gene (Gene ID: 945) in human. CD33 is a single-pass type I membrane sialoadhesion protein that is expressed by myeloid stem cells, myeloblasts, monoblasts, monocytes, macrophages, and granulocyte precursors and preferentially binds to alpha-2,6-linked sialic acid. CD33 is not expressed in erythrocytes, platelets, B-cells, T-cells, and NK cells. Hence, it can serve as a marker for myeloid cells. It is synthesized with a signal peptide (aa 1-17), which is subsequently cleaved off in the mature form. It contains an extracellular domain (aa 18-259), a transmembrane domain (aa 260-282), and a cytoplasmic domain (aa 283-364). CD33 contains two copies of a cytoplasmic motif (aa 338-343 and 356-361), which is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. In the immune response, CD33 may act as an inhibitory receptor upon ligand induced tyrosine phosphorylation by recruiting cytoplasmic phosphatase(s) via their SH2 domain(s) that block signal transduction through dephosphorylation of signaling molecules. Human CD33 is reported to contain two tyrosine residues in its cytoplasmic domain (tyrosine 340 and 358) that when phosphorylated could function as docking sites for the phosphatases, SHP-1 and/or SHP-2, and enable CD33 to function as an inhibitory receptor.