CD22

CD22
Identifiers
Aliases	CD22, SIGLEC-2, SIGLEC2, CD22 molecule
External IDs	OMIM: 107266; MGI: 88322; HomoloGene: 31052; GeneCards: CD22; OMA:CD22 - orthologs
Gene location (Mouse)
Chr.	Chromosome 7 (mouse)
End	30,579,767 bp
RNA expression pattern
	Top expressed in
	spleen; ; appendix; ; lymph node; ; right uterine tube; ; sural nerve; ; corpus callosum; ; putamen; ; inferior olivary nucleus; ; caudate nucleus; ; Amygdala;
	Top expressed in
	spleen; ; mesenteric lymph nodes; ; blood; ; tibiofemoral joint; ; subcutaneous adipose tissue; ; submandibular gland; ; granulocyte; ; calvaria; ; morula; ; tunica adventitia of aorta;
	More reference expression data
	; ; ; ;
	More reference expression data
Gene ontology
Molecular function	protein binding; carbohydrate binding; IgM binding; signaling receptor binding; protein phosphatase binding; sialic acid binding; CD4 receptor binding;
Cellular component	integral component of membrane; plasma membrane; extracellular exosome; membrane; cytoplasm; early endosome; cell surface; neuronal cell body membrane; recycling endosome;
Biological process	cell adhesion; regulation of endocytosis; regulation of B cell proliferation; B cell activation; regulation of immune response; negative regulation of calcium-mediated signaling; negative regulation of B cell receptor signaling pathway;
	Sources:Amigo / QuickGO
Orthologs
	933
	12483
	n/a
	ENSMUSG00000030577
	P20273
	P35329
NM_024916; NM_001185099; NM_001185100; NM_001185101; NM_001278417;
	NM_001771
	NM_001043317; NM_009845
	NP_001172028; NP_001172029; NP_001172030; NP_001265346; NP_001762
	NP_001036782; NP_033975
	Wikidata
View/Edit Human	View/Edit Mouse

CD22, or cluster of differentiation-22, is a molecule belonging to the SIGLEC family of lectins. It is found on the surface of mature B cells and to a lesser extent on some immature B cells. Generally speaking, CD22 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, which specifically binds sialic acid with an immunoglobulin (Ig) domain located at its N-terminus. The presence of Ig domains makes CD22 a member of the immunoglobulin superfamily. CD22 functions as an inhibitory receptor for B cell receptor (BCR) signaling. It 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.