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CD22

Domain

Contains 4 copies of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases.

Function

Mediates B-cell B-cell interactions. May be involved in the localization of B-cells in lymphoid tissues. Binds sialylated glycoproteins; one of which is CD45. Preferentially binds to alpha-2,6-linked sialic acid. The sialic acid recognition site can be masked by cis interactions with sialic acids on the same cell surface. Upon ligand induced tyrosine phosphorylation in the immune response seems to be involved in regulation of B-cell antigen receptor signaling. Plays a role in positive regulation through interaction with Src family tyrosine kinases and may also act as an inhibitory receptor by recruiting cytoplasmic phosphatases via their SH2 domains that block signal transduction through dephosphorylation of signaling molecules.

Post-translational modifications

Phosphorylation of Tyr-762, Tyr-807 and Tyr-822 are involved in binding to SYK, GRB2 and SYK, respectively. Phosphorylation of Tyr-842 is involved in binding to SYK, PLCG2 and PIK3R1/PIK3R2.

Phosphorylated on tyrosine residues by LYN.

Sequence similarities

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

Tissue specificity

B-lymphocytes.

Cellular localization

  • Cell membrane
  • Single-pass type I membrane protein

Alternative names

  • B-cell receptor CD22
  • B-lymphocyte cell adhesion molecule
  • Sialic acid-binding Ig-like lectin 2
  • T-cell surface antigen Leu-14
  • BL-CAM
  • Siglec-2
  • SIGLEC2
  • CD22

Target type

Proteins

Primary research area

Immunology & Infectious Disease

Other research areas

  • Immuno-oncology

Molecular weight

95348Da