Myeloid cell surface antigen CD33 Simoa (CD33 Simoa)
Myeloid Cell Surface Antigen CD33 plays a role in mediating cell-cell interactions and in maintaining immune cells in a resting state. CD33 preferentially recognizes and binds alpha-2,3- and more avidly alpha-2,6-linked sialic acid-bearing glycans. Upon engagement of ligands such as C1q or sialylated glycoproteins, two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) located in CD33 cytoplasmic tail are phosphorylated by Src-like kinases such as LCK. These phosphorylations provide docking sites for the recruitment and activation of protein-tyrosine phosphatases PTPN6/SHP-1 and PTPN11/SHP-2. In turn, these phosphatases regulate downstream pathways through dephosphorylation of signaling molecules. One of the repressive effects of CD33 on monocyte activation requires phosphoinositide 3-kinase/PI3K. Diseases associated with CD33 include Acute Leukemia and Acute Promyelocytic Leukemia.
Swiss-Prot Accession Number: P20138