# CD22

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Lectin molecule

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)[1] Band 7 B1|7 19.26 cM Start 30,564,827 bp[1] End 30,579,767 bp[1] RNA expression pattern Bgee Human Mouse (ortholog) 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 BioGPS 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 Species Human Mouse Entrez 933 12483 Ensembl n/a ENSMUSG00000030577 UniProt P20273 P35329 RefSeq (mRNA) NM_024916 NM_001185099 NM_001185100 NM_001185101 NM_001278417 NM_001771 NM_001043317 NM_009845 RefSeq (protein) NP_001172028 NP_001172029 NP_001172030 NP_001265346 NP_001762 NP_001036782 NP_033975 Location (UCSC) n/a Chr 7: 30.56 – 30.58 Mb PubMed search [2] [3] Wikidata View/Edit Human View/Edit Mouse

**CD22**, or [cluster of differentiation](/source/Cluster_of_differentiation)-22, is a molecule belonging to the [SIGLEC](/source/SIGLEC) family of [lectins](/source/Lectin).[4] 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](/source/Autoimmune_disease).[5]

CD22 is a sugar binding [transmembrane protein](/source/Transmembrane_protein), which specifically binds [sialic acid](/source/Sialic_acid) with an [immunoglobulin (Ig) domain](/source/Immunoglobulin_domain) located at its [N-terminus](/source/N-terminus). The presence of Ig domains makes CD22 a member of the [immunoglobulin superfamily](/source/Immunoglobulin_superfamily). CD22 functions as an inhibitory receptor for [B cell receptor](/source/B_cell_receptor) (BCR) signaling. It is also involved in the B cell trafficking to [Peyer's patches](/source/Peyer's_patch) in mice.[6] In mice, it has been shown that CD22 blockade restores homeostatic [microglial](/source/Microglial) [phagocytosis](/source/Phagocytosis) in aging brains.[7]

image of microglia

## Structure

CD22 is a [transmembrane protein](/source/Transmembrane_protein) with a molecular weight of 140 [kDa](/source/KDa). The extracellular part of CD22 consists of seven [immunoglobulin](/source/Immunoglobulin) domains and the intracellular part is formed by 141-amino acid cytoplasmic tail.[8]

### Extracellular part

The binding site for ligands is located at the extracellular [N-terminus](/source/N-terminus), specifically at the last immunoglobulin domain called the [V-like domain](/source/V-like_domain). This domain binds to ligands containing [sialic acid](/source/Sialic_acid) via α2,6-linkage to the [galactose](/source/Galactose) residue. Such ligands are commonly expressed on the surface of [erythrocytes](/source/Erythrocytes), [monocytes](/source/Monocyte), cytokine-activated endothelial cells, [T cells](/source/T_cell) and [B cells](/source/B_cell). To a lesser extent they are present on soluble [IgM](/source/Immunoglobulin_M) and on the soluble plasmatic glycoprotein called [haptoglobin](/source/Haptoglobin). Therefore, CD22 can bind ligands in the *cis* configuration, when they are on the surface of [B cells](/source/B_cell), or in the *trans* configuration, when they are on the surface of other cells or on soluble glycoproteins or attached to a cell-associated antigen. However, CD22 is masked on most [B-cell](/source/B_cell) surfaces, meaning that it cannot bind exogenous ligands, so cis interaction with [glycoprotein](/source/Glycoprotein) ligands on the same cell is preferred.[9]

#### Trans ligands

Trans interactions between CD22 and its [ligands](/source/Ligand) are important for [B cell](/source/B_cell) [adhesion](/source/Adhesion) and migration. Specifically, CD22-deficient mice have been shown to have reduced numbers of recirculating B cells and reduced numbers of IgM-secreting [plasma cells](/source/Plasma_cell) in the bone marrow. Together, this implies that CD22 interacting with trans ligands is crucial for the homing of mature, recirculating [B cells](/source/B_cell) to the [bone marrow](/source/Bone_marrow).[10]

## BCR signaling

The [intracellular](/source/Intracellular) part of CD22 consists of 6 [tyrosine](/source/Tyrosine) residues which contain both [ITIM](/source/Immunoreceptor_tyrosine-based_inhibitory_motif) and [ITAM motifs](/source/Immunoreceptor_tyrosine-based_activation_motif) suggesting both inhibitory and activation role in signaling.[11] Because of the tyrosine residues, the cytoplasmic domain of CD22 can be [phosphorylated](/source/Protein_phosphorylation). This happens when the BCR is [cross-linked](/source/Cross-link) by the antigen. [Phosphorylation](/source/Phosphorylation) is mediated by Lyn, a [protein tyrosine kinase](/source/Protein_Tyrosine_Kinase) (PTK) of the [Src](/source/Src_family_kinase) family found in [lipid rafts](/source/Lipid_raft).[9]

### Inhibitory role

After CD22 is [phosphorylated](/source/Phosphorylation), the ITIM motifs provide docking sites for the [SH2](/source/SH2_domain) domain containing protein tyrosine phosphatase called [SHP-1](/source/SHP-1). [SHP-1](/source/SHP-1) inhibits [mitogen-activated protein kinase](/source/Mitogen-activated_protein_kinase_kinase) (MAPK) and dephosphorylates components of BCR signaling. That means that association of CD22 with [SHP-1](/source/SHP-1) leads to the inhibition of BCR signaling.[12][9]

### Activation role

After CD22 is phosphorylated, the ITAM motifs provide docking sites for the SH2 domain of Lyn or other Syk kinase or Src-family tyrosine kinases. Thus, CD22 positively regulates BCR signaling and thereby promotes B cell survival.[9]

## Autoimmunity

[Single-nucleotide polymorphisms](/source/Single-nucleotide_polymorphism) in the CD22 gene lead to a higher likelihood of [autoimmune](/source/Autoimmunity) disease. Specifically, some studies show that polymorphisms in the CD22 gene are associated with susceptibility to [systemic lupus erythematosus](/source/Systemic_lupus_erythematosus) (SLE) and cutaneous systemic sclerosis. In addition, mutations in enzymes involved in the glycosylation of the CD22 ligand may also lead to the susceptibility to [autoimmune](/source/Autoimmunity) diseases. Specifically, mutations in the sialic acid esterase were frequently found in patients with [rheumatoid arthritis](/source/Rheumatoid_arthritis) and [SLE](/source/SLE). This enzyme is essential for [deacetylation](/source/Deacetylation) of the N-glycan sialic acid present in CD22 ligands and is therefore crucial for ligand binding.[13]

BCR signaling & inhibitory role

## As a drug target

Because CD22 is restricted to B cells, it is an excellent target for [immunotherapy](/source/Immunotherapy) of [B cell malignancies](/source/B-cell_malignancies). There are several mechanisms by which this can be achieved, namely [monoclonal antibodies](/source/Monoclonal_antibody), [bispecific antibodies](/source/Bispecific_antibodies), [antibody-drug conjugates](/source/Antibody-drug_conjugate), [radioimmunoconjugates](/source/Radioimmunotherapy) or [CAR-T cells](/source/CAR_T_cells).[14]

An immunotoxin, [BL22](/source/BL22) (CAT-3888), that targets this receptor was developed at the [NIH](/source/NIH).[15] BL22 was superseded by [moxetumomab pasudotox](/source/Moxetumomab_pasudotox) (HA22, CAT-8015).[16] Moxetumomab pasudotox is approved in the EU and USA for treatment of relapsed or refractory hairy cell leukemia.[17][18]

### Inotuzumab

It was shown that [antibody-drug conjugates](/source/Antibody-drug_conjugate) work better than naked [antibodies](/source/Antibody). The reason is that CD22 is rapidly [internalized](/source/Internalization_(biology)) rather than being exposed to the extracellular environment making it more suitable for specific delivery of these conjugates.[19] One of such therapeutics is [inotuzumab](/source/Inotuzumab), which was approved by the FDA for the treatment of relapsed or refractory [B cell acute lymphoblastic leukemia](/source/B-cell_acute_lymphoblastic_leukemia) in August 2017.[20] Inotuzumab consists of a CD22-targeting [immunoglobulin G4](/source/Immunoglobulin_G4) [humanized monoclonal antibody](/source/Humanized_monoclonal_antibody) conjugated to [calicheamicin](/source/Calicheamicin). The mechanism by which calicheamicin destroys malignant cells is that it binds to DNA, causing DNA [double-strand breaks](/source/Double-strand_breaks), and this in turn leads to [transcription](/source/Transcription_(biology)) inhibition.[19]

## Interactions

CD22 has been shown to [interact](/source/Protein-protein_interaction) with [Grb2](/source/Grb2),[21][22] [PTPN6](/source/PTPN6),[22][23][24][25][26] [LYN](/source/LYN),[21][24] [SHC1](/source/SHC1)[21] and [INPP5D](/source/INPP5D).[21]

## References

1. ^ [***a***](#cite_ref-refGRCm38Ensembl_1-0) [***b***](#cite_ref-refGRCm38Ensembl_1-1) [***c***](#cite_ref-refGRCm38Ensembl_1-2) [GRCm38: Ensembl release 89: ENSMUSG00000030577](http://May2017.archive.ensembl.org/Mus_musculus/Gene/Summary?db=core;g=ENSMUSG00000030577) – [Ensembl](/source/Ensembl_genome_database_project), May 2017

1. **[^](#cite_ref-2)** ["Human PubMed Reference:"](https://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Link&LinkName=gene_pubmed&from_uid=933). *National Center for Biotechnology Information, U.S. National Library of Medicine*.

1. **[^](#cite_ref-3)** ["Mouse PubMed Reference:"](https://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Link&LinkName=gene_pubmed&from_uid=12483). *National Center for Biotechnology Information, U.S. National Library of Medicine*.

1. **[^](#cite_ref-pmid9498912_4-0)** Crocker PR, Clark EA, Filbin M, Gordon S, Jones Y, Kehrl JH, et al. (February 1998). "Siglecs: a family of sialic-acid binding lectins". *Glycobiology*. **8** (2): v. [doi](/source/Doi_(identifier)):[10.1093/oxfordjournals.glycob.a018832](https://doi.org/10.1093%2Foxfordjournals.glycob.a018832). [PMID](/source/PMID_(identifier)) [9498912](https://pubmed.ncbi.nlm.nih.gov/9498912).

1. **[^](#cite_ref-Hatta1999_5-0)** Hatta Y, Tsuchiya N, Matsushita M, Shiota M, Hagiwara K, Tokunaga K (April 1999). "Identification of the gene variations in human CD22". *Immunogenetics*. **49** (4): 280–286. [doi](/source/Doi_(identifier)):[10.1007/s002510050494](https://doi.org/10.1007%2Fs002510050494). [PMID](/source/PMID_(identifier)) [10079291](https://pubmed.ncbi.nlm.nih.gov/10079291). [S2CID](/source/S2CID_(identifier)) [22947237](https://api.semanticscholar.org/CorpusID:22947237).

1. **[^](#cite_ref-6)** Lee M, Kiefel H, LaJevic MD, Macauley MS, Kawashima H, O'Hara E, et al. (October 2014). ["Transcriptional programs of lymphoid tissue capillary and high endothelium reveal control mechanisms for lymphocyte homing"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4222088). *Nature Immunology*. **15** (10): 982–995. [doi](/source/Doi_(identifier)):[10.1038/ni.2983](https://doi.org/10.1038%2Fni.2983). [PMC](/source/PMC_(identifier)) [4222088](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4222088). [PMID](/source/PMID_(identifier)) [25173345](https://pubmed.ncbi.nlm.nih.gov/25173345).

1. **[^](#cite_ref-J.V._Pluvinage_et_al._7-0)** Pluvinage JV, Haney MS, Smith BA, Sun J, Iram T, Bonanno L, et al. (April 2019). ["CD22 blockade restores homeostatic microglial phagocytosis in ageing brains"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6574119). *Nature*. **568** (7751): 187–192. [Bibcode](/source/Bibcode_(identifier)):[2019Natur.568..187P](https://ui.adsabs.harvard.edu/abs/2019Natur.568..187P). [doi](/source/Doi_(identifier)):[10.1038/s41586-019-1088-4](https://doi.org/10.1038%2Fs41586-019-1088-4). [PMC](/source/PMC_(identifier)) [6574119](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6574119). [PMID](/source/PMID_(identifier)) [30944478](https://pubmed.ncbi.nlm.nih.gov/30944478).

1. **[^](#cite_ref-8)** Tedder TF, Tuscano J, Sato S, Kehrl JH (1997). "CD22, a B lymphocyte-specific adhesion molecule that regulates antigen receptor signaling". *Annual Review of Immunology*. **15**: 481–504. [doi](/source/Doi_(identifier)):[10.1146/annurev.immunol.15.1.481](https://doi.org/10.1146%2Fannurev.immunol.15.1.481). [PMID](/source/PMID_(identifier)) [9143697](https://pubmed.ncbi.nlm.nih.gov/9143697).

1. ^ [***a***](#cite_ref-:0_9-0) [***b***](#cite_ref-:0_9-1) [***c***](#cite_ref-:0_9-2) [***d***](#cite_ref-:0_9-3) Walker JA, Smith KG (March 2008). ["CD22: an inhibitory enigma"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2433339). *Immunology*. **123** (3): 314–325. [doi](/source/Doi_(identifier)):[10.1111/j.1365-2567.2007.02752.x](https://doi.org/10.1111%2Fj.1365-2567.2007.02752.x). [PMC](/source/PMC_(identifier)) [2433339](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2433339). [PMID](/source/PMID_(identifier)) [18067554](https://pubmed.ncbi.nlm.nih.gov/18067554).

1. **[^](#cite_ref-10)** Nitschke L (July 2009). "CD22 and Siglec-G: B-cell inhibitory receptors with distinct functions". *Immunological Reviews*. **230** (1): 128–143. [doi](/source/Doi_(identifier)):[10.1111/j.1600-065X.2009.00801.x](https://doi.org/10.1111%2Fj.1600-065X.2009.00801.x). [PMID](/source/PMID_(identifier)) [19594633](https://pubmed.ncbi.nlm.nih.gov/19594633). [S2CID](/source/S2CID_(identifier)) [205825220](https://api.semanticscholar.org/CorpusID:205825220).

1. **[^](#cite_ref-11)** Poe JC, Fujimoto M, Jansen PJ, Miller AS, Tedder TF (June 2000). ["CD22 forms a quaternary complex with SHIP, Grb2, and Shc. A pathway for regulation of B lymphocyte antigen receptor-induced calcium flux"](https://doi.org/10.1074%2Fjbc.M001892200). *The Journal of Biological Chemistry*. **275** (23): 17420–17427. [doi](/source/Doi_(identifier)):[10.1074/jbc.M001892200](https://doi.org/10.1074%2Fjbc.M001892200). [PMID](/source/PMID_(identifier)) [10748054](https://pubmed.ncbi.nlm.nih.gov/10748054).

1. **[^](#cite_ref-12)** Sato S, Tuscano JM, Inaoki M, Tedder TF (August 1998). "CD22 negatively and positively regulates signal transduction through the B lymphocyte antigen receptor". *Seminars in Immunology*. **10** (4): 287–297. [doi](/source/Doi_(identifier)):[10.1006/smim.1998.0121](https://doi.org/10.1006%2Fsmim.1998.0121). [PMID](/source/PMID_(identifier)) [9695185](https://pubmed.ncbi.nlm.nih.gov/9695185).

1. **[^](#cite_ref-13)** Clark EA, Giltiay NV (2018). ["CD22: A Regulator of Innate and Adaptive B Cell Responses and Autoimmunity"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6173129). *Frontiers in Immunology*. **9** 2235. [doi](/source/Doi_(identifier)):[10.3389/fimmu.2018.02235](https://doi.org/10.3389%2Ffimmu.2018.02235). [PMC](/source/PMC_(identifier)) [6173129](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6173129). [PMID](/source/PMID_(identifier)) [30323814](https://pubmed.ncbi.nlm.nih.gov/30323814).

1. **[^](#cite_ref-14)** Shah NN, Sokol L (2021). ["Targeting CD22 for the Treatment of B-Cell Malignancies"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8275043). *ImmunoTargets and Therapy*. **10**: 225–236. [doi](/source/Doi_(identifier)):[10.2147/ITT.S288546](https://doi.org/10.2147%2FITT.S288546). [PMC](/source/PMC_(identifier)) [8275043](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8275043). [PMID](/source/PMID_(identifier)) [34262884](https://pubmed.ncbi.nlm.nih.gov/34262884).

1. **[^](#cite_ref-titleBL22_Immunotoxin_in_Treating_Patients_Previously_Treated_With_Cladribine_for_Hairy_Cell_Leukemia_-_Full_Text_View_-_ClinicalTrials.gov_15-0)** Clinical trial number *[NCT00074048](https://www.clinicaltrials.gov/show/NCT00074048)* for "BL22 Immunotoxin in Treating Patients Previously Treated With Cladribine for Hairy Cell Leukemia" at [ClinicalTrials.gov](/source/ClinicalTrials.gov)

1. **[^](#cite_ref-CAT-pdf_16-0)** ["CAT-3888, CAT-8015 and CAT-5001"](https://web.archive.org/web/20070227180215/http://www.cambridgeantibody.com/__data/assets/pdf_file/10857/CAT-3888%2C_CAT-8015_and_CAT-5001_Nov06.pdf) (PDF). *Cambridge Antibody Technology*. Archived from [the original](http://www.cambridgeantibody.com/__data/assets/pdf_file/10857/CAT-3888,_CAT-8015_and_CAT-5001_Nov06.pdf) (PDF) on 2007-02-27.

1. **[^](#cite_ref-Lumoxiti_EPAR_17-0)** ["Lumoxiti EPAR"](https://www.ema.europa.eu/en/medicines/human/EPAR/lumoxiti). *[European Medicines Agency](/source/European_Medicines_Agency) (EMA)*. 9 December 2020. Retrieved 16 July 2021..

1. **[^](#cite_ref-18)** ["Moxetumomab pasudotox-tdfk FDA Approval"](https://www.accessdata.fda.gov/scripts/opdlisting/oopd/detailedIndex.cfm?cfgridkey=248707). *U.S. [Food and Drug Administration](/source/Food_and_Drug_Administration) (FDA)*. Retrieved 20 April 2020.[*[dead link](https://en.wikipedia.org/wiki/Wikipedia:Link_rot)*]

1. ^ [***a***](#cite_ref-:1_19-0) [***b***](#cite_ref-:1_19-1) Wynne J, Wright D, Stock W (January 2019). ["Inotuzumab: from preclinical development to success in B-cell acute lymphoblastic leukemia"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6325303). *Blood Advances*. **3** (1): 96–104. [doi](/source/Doi_(identifier)):[10.1182/bloodadvances.2018026211](https://doi.org/10.1182%2Fbloodadvances.2018026211). [PMC](/source/PMC_(identifier)) [6325303](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6325303). [PMID](/source/PMID_(identifier)) [30622147](https://pubmed.ncbi.nlm.nih.gov/30622147).

1. **[^](#cite_ref-20)** ["FDA approves inotuzumab ozogamicin for relapsed or refractory B-cell precursor ALL"](https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-inotuzumab-ozogamicin-relapsed-or-refractory-b-cell-precursor-all). *Center for Drug Evaluation and Research*. U.S. Food and Drug Administration (FDA). 2019-02-09.

1. ^ [***a***](#cite_ref-pmid10748054_21-0) [***b***](#cite_ref-pmid10748054_21-1) [***c***](#cite_ref-pmid10748054_21-2) [***d***](#cite_ref-pmid10748054_21-3) Poe JC, Fujimoto M, Jansen PJ, Miller AS, Tedder TF (June 2000). ["CD22 forms a quaternary complex with SHIP, Grb2, and Shc. A pathway for regulation of B lymphocyte antigen receptor-induced calcium flux"](https://doi.org/10.1074%2Fjbc.M001892200). *The Journal of Biological Chemistry*. **275** (23): 17420–17427. [doi](/source/Doi_(identifier)):[10.1074/jbc.M001892200](https://doi.org/10.1074%2Fjbc.M001892200). [PMID](/source/PMID_(identifier)) [10748054](https://pubmed.ncbi.nlm.nih.gov/10748054).

1. ^ [***a***](#cite_ref-pmid11551923_22-0) [***b***](#cite_ref-pmid11551923_22-1) Otipoby KL, Draves KE, Clark EA (November 2001). ["CD22 regulates B cell receptor-mediated signals via two domains that independently recruit Grb2 and SHP-1"](https://doi.org/10.1074%2Fjbc.M105446200). *The Journal of Biological Chemistry*. **276** (47): 44315–44322. [doi](/source/Doi_(identifier)):[10.1074/jbc.M105446200](https://doi.org/10.1074%2Fjbc.M105446200). [PMID](/source/PMID_(identifier)) [11551923](https://pubmed.ncbi.nlm.nih.gov/11551923).

1. **[^](#cite_ref-pmid9890995_23-0)** Blasioli J, Paust S, Thomas ML (January 1999). ["Definition of the sites of interaction between the protein tyrosine phosphatase SHP-1 and CD22"](https://doi.org/10.1074%2Fjbc.274.4.2303). *The Journal of Biological Chemistry*. **274** (4): 2303–2307. [doi](/source/Doi_(identifier)):[10.1074/jbc.274.4.2303](https://doi.org/10.1074%2Fjbc.274.4.2303). [PMID](/source/PMID_(identifier)) [9890995](https://pubmed.ncbi.nlm.nih.gov/9890995).

1. ^ [***a***](#cite_ref-pmid10228003_24-0) [***b***](#cite_ref-pmid10228003_24-1) Greer SF, Justement LB (May 1999). ["CD45 regulates tyrosine phosphorylation of CD22 and its association with the protein tyrosine phosphatase SHP-1"](https://doi.org/10.4049%2Fjimmunol.162.9.5278). *Journal of Immunology*. **162** (9): 5278–5286. [doi](/source/Doi_(identifier)):[10.4049/jimmunol.162.9.5278](https://doi.org/10.4049%2Fjimmunol.162.9.5278). [PMID](/source/PMID_(identifier)) [10228003](https://pubmed.ncbi.nlm.nih.gov/10228003). [S2CID](/source/S2CID_(identifier)) [2223820](https://api.semanticscholar.org/CorpusID:2223820).

1. **[^](#cite_ref-pmid8627166_25-0)** Law CL, Sidorenko SP, Chandran KA, Zhao Z, Shen SH, Fischer EH, et al. (February 1996). ["CD22 associates with protein tyrosine phosphatase 1C, Syk, and phospholipase C-gamma(1) upon B cell activation"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2192439). *The Journal of Experimental Medicine*. **183** (2): 547–560. [doi](/source/Doi_(identifier)):[10.1084/jem.183.2.547](https://doi.org/10.1084%2Fjem.183.2.547). [PMC](/source/PMC_(identifier)) [2192439](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2192439). [PMID](/source/PMID_(identifier)) [8627166](https://pubmed.ncbi.nlm.nih.gov/8627166).

1. **[^](#cite_ref-pmid11356834_26-0)** Adachi T, Wienands J, Wakabayashi C, Yakura H, Reth M, Tsubata T (July 2001). ["SHP-1 requires inhibitory co-receptors to down-modulate B cell antigen receptor-mediated phosphorylation of cellular substrates"](https://doi.org/10.1074%2Fjbc.M100997200). *The Journal of Biological Chemistry*. **276** (28): 26648–26655. [doi](/source/Doi_(identifier)):[10.1074/jbc.M100997200](https://doi.org/10.1074%2Fjbc.M100997200). [PMID](/source/PMID_(identifier)) [11356834](https://pubmed.ncbi.nlm.nih.gov/11356834).

## External links

- [CD22+Antigen](https://meshb.nlm.nih.gov/record/ui?name=CD22+Antigen) at the U.S. National Library of Medicine [Medical Subject Headings](/source/Medical_Subject_Headings) (MeSH)

- Human [*CD22*](https://genome.ucsc.edu/cgi-bin/hgTracks?db=hg38&singleSearch=knownCanonical&position=CD22) genome location and [*CD22*](https://genome.ucsc.edu/cgi-bin/hgGene?db=hg38&hgg_type=knownGene&hgg_gene=CD22) gene details page in the [UCSC Genome Browser](/source/UCSC_Genome_Browser).

- Overview of all the structural information available in the [PDB](/source/Protein_Data_Bank) for [UniProt](/source/UniProt): *[P20273](https://www.ebi.ac.uk/pdbe/pdbe-kb/proteins/P20273)* (B-cell receptor CD22) at the [PDBe-KB](/source/PDBe-KB).

v t e Proteins: clusters of differentiation (see also list of human clusters of differentiation) 1–50 CD1 a-c 1A 1B 1D 1E CD2 CD3 γ δ ε CD4 CD5 CD6 CD7 CD8 a CD9 CD10 CD11 a b c d CD13 CD14 CD15 CD16 A B CD18 CD19 CD20 CD21 CD22 CD23 CD24 CD25 CD26 CD27 CD28 CD29 CD30 CD31 CD32 A B CD33 CD34 CD35 CD36 CD37 CD38 CD39 CD40 CD41 CD42 a b c d CD43 CD44 CD45 CD46 CD47 CD48 CD49 a b c d e f CD50 51–100 CD51 CD52 CD53 CD54 CD55 CD56 CD57 CD58 CD59 CD61 CD62 E L P CD63 CD64 A B C CD66 a b c d e f CD68 CD69 CD70 CD71 CD72 CD73 CD74 CD78 CD79 a b CD80 CD81 CD82 CD83 CD84 CD85 a d e h j k CD86 CD87 CD88 CD89 CD90 CD91 CD92 CD93 CD94 CD95 CD96 CD97 CD98 CD99 CD100 101–150 CD101 CD102 CD103 CD104 CD105 CD106 CD107 a b CD108 CD109 CD110 CD111 CD112 CD113 CD114 CD115 CD116 CD117 CD118 CD119 CD120 a b CD121 a b CD122 CD123 CD124 CD125 CD126 CD127 CD129 CD130 CD131 CD132 CD133 CD134 CD135 CD136 CD137 CD138 CD140b CD141 CD142 CD143 CD144 CD146 CD147 CD148 CD150 151–200 CD151 CD152 CD153 CD154 CD155 CD156 a b c CD157 CD158 (a d e i k) CD159 a c CD160 CD161 CD162 CD163 CD164 CD166 CD167 a b CD168 CD169 CD170 CD171 CD172 a b g CD174 CD177 CD178 CD179 a b CD180 CD181 CD182 CD183 CD184 CD185 CD186 CD191 CD192 CD193 CD194 CD195 CD196 CD197 CDw198 CDw199 CD200 201–250 CD201 CD202b CD204 CD205 CD206 CD207 CD208 CD209 CDw210 a b CD212 CD213a 1 2 CD217 CD218 (a b) CD220 CD221 CD222 CD223 CD224 CD225 CD226 CD227 CD228 CD229 CD230 CD233 CD234 CD235 a b CD236 CD238 CD239 CD240CE CD240D CD241 CD243 CD244 CD246 CD247 CD248 CD249 251–300 CD252 CD253 CD254 CD256 CD257 CD258 CD261 CD262 CD263 CD264 CD265 CD266 CD267 CD268 CD269 CD271 CD272 CD273 CD274 CD275 CD276 CD278 CD279 CD280 CD281 CD282 CD283 CD284 CD286 CD288 CD289 CD290 CD292 CDw293 CD294 CD295 CD297 CD298 CD299 301–350 CD300A CD301 CD302 CD303 CD304 CD305 CD306 CD307 CD309 CD312 CD314 CD315 CD316 CD317 CD318 CD320 CD321 CD322 CD324 CD325 CD326 CD327 CD328 CD329 CD331 CD332 CD333 CD334 CD335 CD336 CD337 CD338 CD339 CD340 CD344 CD349 CD350 351–371 CD351 CD352 CD353 CD354 CD355 CD357 CD358 CD360 CD361 CD362 CD363 CD364 CD365 CD366 CD367 CD368 CD369 CD370 CD371 Category Commons

v t e Protein: lectins Animal C-type lectins Asialoglycoprotein receptor KLRD1 Collectin Mannan-binding lectin Mannose receptor proteochondroitin sulfate Aggrecan Versican Brevican Neurocan SIGLEC Sialoadhesin CD22 CD33 Myelin-associated glycoprotein SIGLEC5 SIGLEC6 SIGLEC7 SIGLEC8 SIGLEC9 SIGLEC10 SIGLEC12 Other Calnexin Calreticulin Galectin N-Acetylglucosamine receptor Selectin Plant Toxalbumins Abrin Ricin Mitogens Concanavalin A Phytohaemagglutinin Pokeweed mitogen Legume lectin BanLec

v t e Membrane proteins: cell adhesion molecules Calcium-independent IgSF CAM N-CAM (Myelin protein zero) ICAM (1, 5) VCAM-1 PE-CAM L1 family L1-CAM NRCAM NFASC CHL1 Nectin PVRL1 PVRL2 PVRL3 CADM1 CADM3 CD155 Integrins LFA-1 (CD11a+CD18) Integrin alphaXbeta2 (CD11c+CD18) Macrophage-1 antigen (CD11b+CD18) VLA-4 (CD49d+CD29) Glycoprotein IIb/IIIa (ITGA2B+ITGB3) Calcium-dependent Cadherins Classical CDH1 CDH2 CDH3 Desmosomal Desmoglein (DSG1, DSG2, DSG3, DSG4) Desmocollin (DSC1, DSC2, DSC3) Protocadherin PCDH1 PCDH15 PCDH19 Unconventional/ungrouped T-cadherin CDH4 CDH5 CDH6 CDH8 CDH11 CDH12 CDH15 CDH16 CDH17 CDH9 CDH10 Selectins E-selectin L-selectin P-selectin Other Lymphocyte homing receptor: CD44 L-selectin integrin (VLA-4, LFA-1) Carcinoembryonic antigen CD24 CD44 CD146 EpCAM

v t e Transmembrane receptors: immunoglobulin superfamily immune receptors Antibody receptor: Fc receptor Epsilon (ε) FcεRI (FcεRII is C-type lectin) Gamma (γ) FcγRI FcγRII FcγRIII Neonatal Alpha (α)/mu (μ) FcαRI Fcα/μR Secretory Polymeric immunoglobulin receptor Antigen receptor B cells Antigen receptor BCR Co-receptor stimulate: CD21/CD19/CD81 inhibit: CD22 Accessory molecules Ig-α/Ig-β (CD79) T cells Ligands MHC MHC class I MHC class II Antigen receptor TCR: TRA@ TRB@ TRD@ TRG@ Co-receptors CD8 (with two glycoprotein chains CD8α and CD8β) CD4 Accessory molecules CD3 CD3γ CD3δ CD3ε CD3ζ Cytokine receptor see cytokine receptors Killer-cell IG-like receptors KIR2DL1 KIR2DL2 KIR2DL3 KIR2DL4 KIR2DL5A KIR2DL5B KIR2DS1 KIR2DS2 KIR2DS3 KIR2DS4 KIR2DS5 KIR3DL1 KIR3DL2 KIR3DL3 KIR3DS1 Leukocyte IG-like receptors LILRA1 LILRA2 LILRA3 LILRA4 LILRA5 LILRA6 LILRB1 LILRB2 LILRB3 LILRB4 LILRB5

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Adapted from the Wikipedia article [CD22](https://en.wikipedia.org/wiki/CD22) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/CD22?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.