| Tissue Specificity | B-lymphocytes. |
| 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. |
| Function | Most highly expressed siglec (sialic acid-binding immunoglobulin-like lectin) on B-cells that plays a role in various aspects of B-cell biology including differentiation, antigen presentation, and trafficking to bone marrow. Binds to alpha 2,6-linked sialic acid residues of surface molecules such as CD22 itself, CD45 and IgM in a cis configuration. Can also bind to ligands on other cells as an adhesion molecule in a trans configuration. Acts as an inhibitory coreceptor on the surface of B-cells and inhibits B-cell receptor induced signaling, characterized by inhibition of the calcium mobilization and cellular activation. Mechanistically, the immunoreceptor tyrosine-based inhibitory motif domain is phosphorylated by the Src kinase LYN, which in turn leads to the recruitment of the protein tyrosine phosphatase 1/PTPN6, leading to the negative regulation of BCR signaling. If this negative signaling from is of sufficient strength, apoptosis of the B-cell can be induced. |
| Protein Name | B-Cell Receptor Cd22B-Lymphocyte Cell Adhesion MoleculeBl-CamSialic Acid-Binding Ig-Like Lectin 2Siglec-2T-Cell Surface Antigen Leu-14Cd Antigen Cd22 |
| Database Links | Reactome: R-HSA-198933Reactome: R-HSA-5690714Reactome: R-HSA-983695 |
| Cellular Localisation | Cell MembraneSingle-Pass Type I Membrane Protein |
| Alternative Protein Names | B-Cell Receptor Cd22 proteinB-Lymphocyte Cell Adhesion Molecule proteinBl-Cam proteinSialic Acid-Binding Ig-Like Lectin 2 proteinSiglec-2 proteinT-Cell Surface Antigen Leu-14 proteinCd Antigen Cd22 proteinCD22 proteinSIGLEC2 protein |
Information sourced from Uniprot.org
