CD22
CD22 (CD22 molecule, SIGLEC-2, SIGLEC2) is a sialic acid-binding immunoglobulin-like lectin and the most highly expressed siglec on B-cells. It acts as an inhibitory coreceptor that restrains B-cell receptor signalling. Browse Assay Genie's current range of CD22 research reagents below, or read on for the biology behind the target.
CD22 is the most highly expressed siglec on B-cells and contributes to several aspects of B-cell biology, including differentiation, antigen presentation and trafficking to bone marrow. It binds alpha 2,6-linked sialic acid residues on surface molecules such as CD22 itself, CD45 and IgM in a cis configuration, and it can also engage ligands on other cells as an adhesion molecule in a trans configuration.
Functionally, CD22 is an inhibitory coreceptor on the B-cell surface that dampens B-cell receptor (BCR) induced signalling, shown by reduced calcium mobilisation and cellular activation. Its immunoreceptor tyrosine-based inhibitory motif is phosphorylated by the Src kinase LYN, which recruits the protein tyrosine phosphatase PTPN6 (SHP-1) and so negatively regulates BCR signalling. If this negative signal is strong enough, apoptosis of the B-cell can be induced.
The CD22 gene encodes a member of the immunoglobulin superfamily and the SIGLEC family. HGNC places it among the CD molecules, C2-set domain containing genes and sialic acid binding Ig like lectins, and also lists it as a microRNA protein coding host gene. It was previously designated the CD22 antigen, and the mouse ortholog is Cd22. NCBI Gene annotation links the protein to B cell activation, negative regulation of the B cell receptor signalling pathway and regulation of endocytosis, with localisation to early and recycling endosomes, and notes an association with diffuse large B-cell lymphoma. Researchers studying the CD22 protein often work alongside other B-cell markers such as CD19.
CD22 recruits PTPN6 after LYN phosphorylation of its inhibitory motif, making it a key model for negative regulation of BCR signalling.
CD22 binds alpha 2,6-linked sialic acids on CD45, IgM and itself in cis, and can bind ligands on other cells in trans.
CD22 is implicated in B-cell differentiation, antigen presentation and trafficking to bone marrow.
CD22 is implicated in diffuse large B-cell lymphoma, and it is highly expressed on B-cells.
CD22 is an inhibitory coreceptor on B-cells. After LYN phosphorylates its inhibitory motif, PTPN6 is recruited and BCR-induced signalling, including calcium mobilisation and activation, is reduced. Strong negative signalling can induce B-cell apoptosis. It also binds sialic acid ligands in cis and trans.
CD22 is also called SIGLEC-2 or SIGLEC2, reflecting its place in the sialic acid-binding Ig-like lectin family. UniProt names it B-cell receptor CD22, HGNC names the gene CD22 molecule, and an earlier name was CD22 antigen.
The mouse has an ortholog, Cd22, so rodent models can be used for B-cell studies; check the datasheet of any product for its validated reactivity. NCBI Gene reports that CD22 is implicated in diffuse large B-cell lymphoma.
Other CD molecules and immune-cell markers that are useful alongside CD22 in B-cell research.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P20273; product specifications from Assay Genie datasheets.