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B-cell receptor CD22; sialic acid-binding Ig-like lectin 2; siglec-2; Leu-14; B-lymphocyte cell adhesion molecule; BL-CAM (CD22, SIGLEC2)
Function:
- mediates B-cell B-cell interactions
- may be involved in localization of B-cells in lymphoid tissues
- binds sialylated glycoproteins; one of which is CD45
- preferentially binds to alpha-2,6-linked sialic acid
- the sialic acid recognition site can be masked by cis interactions with sialic acids on the same cell surface
- ligand induced tyrosine phosphorylation seems to play a role regulation of B-cell antigen receptor signaling
- plays a role in positive regulation through interaction with Src family tyrosine kinases & may also act as an inhibitory receptor by recruiting cytoplasmic phosphatases via their SH2 domains that block signal transduction through dephosphorylation of signaling molecules
- phosphorylation of Tyr-762, Tyr-807 & Tyr-822 are involved in binding to SYK, GRB2 & SYK, respectively
- phosphorylation of Tyr-842 is involved in binding to SYK, PLCG2 & PIK3R1/PIK3R2
- phosphorylated on Tyr by LYN (putative)
- interacts with PTPN6/SHP-1, LYN, SYK, PIK3R1/PIK3R2 & PLCG1 upon phosphorylation
- interacts with GRB2, INPP5D & SHC1 upon phosphorylation (putative)
- may form a complex with INPP5D/SHIP, GRB2 & SHC1
Structure:
- predominantly monomer of isoform CD22-beta
- also found as heterodimer of isoform CD22-beta & a shorter isoform
- contains 4 copies of an ITIM motif
- belongs to the immunoglobulin superfamily, SIGLEC (sialic acid binding Ig-like lectin) family
- contains 6 Ig-like C2-type domains (immunoglobulin-like)
- contains 1 Ig-like V-type domain (immunoglobulin-like)
Compartment:
- cell membrane; single-pass type I membrane protein
Alternative splicing: named isoforms=2; CD22-beta; CD22-alpha
Expression:
- resting B-cells
- plasma cells stain negatively with antibody
Pathology:
- expressed in B cell ALL
Laboratory:
- CD22 cells in body fluid
- CD22 cells in blood
- CD22 blasts in specimen
- cytoplasmic CD22 blasts in specimen
- CD22 blasts in blood
- cytoplasmic CD22 blasts in blood
- CD22 blasts in bone marrow
- cytoplasmic CD22 blasts in bone marrow
Pharmacology:
- moxetumomab, an anti-CD22 monoclonal Ab FDA-approved to treat refractory hairy cell leukemia
Related
CD22 Ag in tissue
CD22 cells in specimen
General
cluster-of-differentiation antigen; cluster designation antigen; CD antigen
cell surface receptor
glycoprotein
phosphoprotein
Properties
SIZE: entity length = 847 aa
MW = 95 kD
COMPARTMENT: cellular membrane
MOTIF: signal sequence {1-19}
immunoglobulin superfamily domain {20-138}
MOTIF: cysteine residue {C39}
MODIFICATION: cysteine residue {C167}
cysteine residue {C44}
MODIFICATION: cysteine residue {C102}
N-glycosylation site {N67}
N-glycosylation site {N101}
cysteine residue {C102}
MODIFICATION: cysteine residue {C44}
N-glycosylation site {N112}
binding site
SITE: 120-120
FOR-BINDING-OF: Sialic acid
N-glycosylation site {N135}
immunoglobulin superfamily domain {143-235}
MOTIF: cysteine residue {C161}
MODIFICATION: cysteine residue {C219}
N-glycosylation site {N164}
cysteine residue {C167}
MODIFICATION: cysteine residue {C39}
cysteine residue {C219}
MODIFICATION: cysteine residue {C161}
N-glycosylation site {N231}
immunoglobulin superfamily domain {242-326}
MOTIF: cysteine residue {C265}
MODIFICATION: cysteine residue {C309}
cysteine residue {C309}
MODIFICATION: cysteine residue {C265}
immunoglobulin superfamily domain {331-416}
MOTIF: cysteine residue {C353}
MODIFICATION: cysteine residue {C396}
N-glycosylation site {N363}
cysteine residue {C396}
MODIFICATION: cysteine residue {C353}
immunoglobulin superfamily domain {419-500}
MOTIF: cysteine residue {C442}
MODIFICATION: cysteine residue {C484}
N-glycosylation site {N445}
N-glycosylation site {N448}
N-glycosylation site {N479}
cysteine residue {C484}
MODIFICATION: cysteine residue {C442}
immunoglobulin superfamily domain {505-582}
MOTIF: cysteine residue {C529}
MODIFICATION: cysteine residue {C571}
cysteine residue {C571}
MODIFICATION: cysteine residue {C529}
N-glycosylation site {N574}
immunoglobulin superfamily domain {593-676}
MOTIF: cysteine residue {C616}
MODIFICATION: cysteine residue {C659}
N-glycosylation site {N634}
cysteine residue {C659}
MODIFICATION: cysteine residue {C616}
transmembrane domain {688-706}
peptide motif {760-765}
MOTIF: Tyr phosphorylation site {Y762}
peptide motif {794-799}
Tyr phosphorylation site {Y807}
peptide motif {820-825}
MOTIF: Tyr phosphorylation site {Y822}
peptide motif {840-845}
MOTIF: Tyr phosphorylation site {Y842}
Database Correlations
OMIM 107266
UniProt P20273
PFAM correlations
Entrez Gene 933
Kegg hsa:933
References
- UniProt :accession P20273
- Functional glycomics gateway - glycan binding
Note: siglec-2 [3 Fc domains]
http://www.functionalglycomics.org/glycomics/GBPServlet?&operationtype=view&cbpId=cbp_hum_Itlect_00001
- Functional glycomics gateway - glycan binding
Note: siglec-2
http://www.functionalglycomics.org/glycomics/GBPServlet?&operationtype=view&cbpId=cbp_hum_Itlect_269
- http://www.pathologyoutlines.com/cdmarkers.html
15 October 2002