CD22

CD22 molecule
Identifiers
Symbols	CD22 ; SIGLEC-2; SIGLEC2
External IDs	OMIM: 107266 MGI: 88322 HomoloGene: 31052 ChEMBL: 3218 GeneCards: CD22 Gene
Gene ontology Molecular function • protein binding • carbohydrate binding Cellular component • integral component of plasma membrane • external side of plasma membrane • extracellular exosome Biological process • cell adhesion Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	933	12483
Ensembl	ENSG00000012124	ENSMUSG00000030577
UniProt	P20273	P35329
RefSeq (mRNA)	NM_001185099	NM_001043317
RefSeq (protein)	NP_001172028	NP_001036782
Location (UCSC)	Chr 19: 35.32 – 35.35 Mb	Chr 7: 30.87 – 30.88 Mb
PubMed search	[1]	[2]

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.

An immunotoxin, BL22, that targets this receptor is being tested at the NIH.

External links

• CD22 Antigen at the US National Library of Medicine Medical Subject Headings (MeSH)

Interactions

CD22 has been shown to interact with Grb2, PTPN6, LYN, SHC1 and INPP5D.