CD22

Description

The CD22 (CD22 molecule) is a protein-coding gene located on chromosome 19.

CD22, or cluster of differentiation-22, is a member of the SIGLEC family of lectins found on the surface of mature B cells and to a lesser extent on some immature B cells. It is a regulatory molecule that prevents the overactivation of the immune system and the development of autoimmune diseases. CD22 is a sugar-binding transmembrane protein that specifically binds sialic acid with an immunoglobulin (Ig) domain located at its N-terminus. This makes CD22 a member of the immunoglobulin superfamily. CD22 functions as an inhibitory receptor for B cell receptor (BCR) signaling and is also involved in the B cell trafficking to Peyer's patches in mice. In mice, it has been shown that CD22 blockade restores homeostatic microglial phagocytosis in aging brains. CD22 is a transmembrane protein with a molecular weight of 140 kDa. Its extracellular part consists of seven immunoglobulin domains, and its intracellular part is formed by a 141-amino acid cytoplasmic tail.

CD22 mediates interactions between B cells and may play a role in their localization within lymphoid tissues. It binds to sialylated glycoproteins, including CD45, preferentially binding to alpha-2,6-linked sialic acid. Its sialic acid recognition site can be masked by interactions with sialic acids on the same cell surface. Upon ligand-induced tyrosine phosphorylation during an immune response, CD22 appears to regulate B-cell antigen receptor signaling. It can participate in positive regulation through interactions with Src family tyrosine kinases and may also act as an inhibitory receptor by recruiting cytoplasmic phosphatases via their SH2 domains. These phosphatases block signal transduction by dephosphorylating signaling molecules.

CD22 is also known as SIGLEC-2, SIGLEC2.

Associated Diseases

WES Whole Exome Sequencing

Clinical Exome Sequencing