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Reviewed, UniProtKB/Swiss-Prot P20273 (CD22_HUMAN)

Last modified July 22, 2008. Version 100. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (7) | Third-party data | Customize display text xml rdf/xml gff fasta
Names and origin · Protein attributes · General annotation (Comments) · Ontologies · Binary interactions · Alternative products · Sequence annotation (Features) · Sequences · References · Cross-references · Entry information · Relevant documents

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Names and origin

Protein namesRecommended name:
    B-cell receptor CD22
Alternative name(s):
    Sialic acid-binding Ig-like lectin 2
      Short name(s)=Siglec-2
    Leu-14
    B-lymphocyte cell adhesion molecule
      Short name(s)=BL-CAM
    CD_antigen=CD22
Gene names
Name: CD22
Synonyms: SIGLEC2
OrganismHomo sapiens (Human)
Taxonomic identifier9606 [NCBI]
Taxonomic lineageEukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Primates › Haplorrhini › Catarrhini › Hominidae › Homo

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Protein attributes

Sequence length847 AA.
Sequence statusComplete.
Sequence processingThe displayed sequence is further processed into a mature form.
Protein existenceEvidence at protein level.

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General annotation (Comments)

Function

Mediates B-cell B-cell interactions. May be involved in the localization of B-cells in lymphoid tissues. Binds sialylated glycoproteins; one of which is CD45. Preferentially binds to alpha2,6-linked sialic acid. The sialic acid recognition site can be masked by cis interactions with sialic acids on the same cell surface. Upon ligand induced tyrosine phosphorylation in the immune response seems to be involved in regulation of B-cell antigen receptor signaling. Plays a role in positive regulation through interaction with Src family tyrosine kinases and may also act as an inhibitory receptor by recruiting cytoplasmic phosphatases via their SH2 domains that block signal transduction through dephosphorylation of signaling molecules.

Subunit structure

Predominantly monomer of isoform CD22-beta. Also found as heterodimer of isoform CD22-beta and a shorter isoform. Interacts with PTPN6/SHP-1, LYN, SYK, PIK3R1/PIK3R2 and PLCG1 upon phosphorylation. Interacts with GRB2, INPP5D and SHC1 upon phosphorylation By similarity. May form a complex with INPP5D/SHIP, GRB2 and SHC1.

Subcellular location

Cell membrane; Single-pass type I membrane protein.

Tissue specificity

B-lymphocytes.

Domain

Contains 4 copies of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases.

Post-translational modification

Phosphorylation of Tyr-762, Tyr-807 and Tyr-822 are involved in binding to SYK, GRB2 and SYK, respectively. Phosphorylation of Tyr-842 is involved in binding to SYK, PLCG2 and PIK3R1/PIK3R2.

Phosphorylated on tyrosine residues by LYN By similarity.

Sequence similarities

Belongs to the immunoglobulin superfamily. SIGLEC (sialic acid binding Ig-like lectin) family.

Contains 6 Ig-like C2-type (immunoglobulin-like) domains.

Contains 1 Ig-like V-type (immunoglobulin-like) domain.

Sequence caution

CAA36988.1 sequence differs from that shown. Reason: Frameshift at position 806.

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Ontologies

Keywords

   Biological processCell adhesion
   Cellular componentCell membrane
Membrane
   Coding sequence diversityAlternative splicing
Polymorphism
   DomainImmunoglobulin domain
Repeat
Signal
Transmembrane
   LigandLectin
   PTMGlycoprotein
Phosphoprotein

Gene Ontology (GO)

   Biological processcell adhesion

Non-traceable author statement. Source: ProtInc

   Molecular functionprotein binding Ref.8 Ref.9

Inferred from physical interaction. Source: IntAct

Complete GO annotation...

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Alternative products

This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]

Notes: Additional isoforms seem to exist.
Isoform CD22-beta (identifier: P20273-1)

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.
Isoform CD22-alpha (identifier: P20273-2)

The sequence of this isoform differs from the canonical sequence as follows:
     241-417: Missing.

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Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical view

Molecule processing

Signal peptide1 – 1919 Potential
Chain20 – 847828B-cell receptor CD22

Regions

Topological domain20 – 687668Extracellular Potential
Transmembrane688 – 70619 Potential
Topological domain707 – 847141Cytoplasmic Potential
Domain20 – 138119Ig-like V-type
Domain143 – 23593Ig-like C2-type 1
Domain242 – 32685Ig-like C2-type 2
Domain331 – 41686Ig-like C2-type 3
Domain419 – 50082Ig-like C2-type 4
Domain505 – 58278Ig-like C2-type 5
Domain593 – 67684Ig-like C2-type 6
Motif760 – 7656ITIM motif 1
Motif794 – 7996ITIM motif 2
Motif820 – 8256ITIM motif 3
Motif840 – 8456ITIM motif 4

Sites

Binding site1201Sialic acid By similarity

Amino acid modifications

Modified residue7621Phosphotyrosine By similarity
Modified residue8071Phosphotyrosine By similarity
Modified residue8221Phosphotyrosine By similarity
Modified residue8421Phosphotyrosine By similarity
Glycosylation671N-linked (GlcNAc...) Potential
Glycosylation1011N-linked (GlcNAc...) Potential
Glycosylation1121N-linked (GlcNAc...) Potential
Glycosylation1351N-linked (GlcNAc...) Potential
Glycosylation1641N-linked (GlcNAc...) Potential
Glycosylation2311N-linked (GlcNAc...) Potential
Glycosylation3631N-linked (GlcNAc...) Potential
Glycosylation4451N-linked (GlcNAc...) Potential
Glycosylation4481N-linked (GlcNAc...) Potential
Glycosylation4791N-linked (GlcNAc...) Potential
Glycosylation5741N-linked (GlcNAc...) Potential
Glycosylation6341N-linked (GlcNAc...) Potential
Disulfide bond39 ↔ 167 By similarity
Disulfide bond44 ↔ 102 By similarity
Disulfide bond161 ↔ 219 By similarity
Disulfide bond265 ↔ 309 By similarity
Disulfide bond353 ↔ 396 By similarity
Disulfide bond442 ↔ 484 By similarity
Disulfide bond529 ↔ 571 By similarity
Disulfide bond616 ↔ 659 By similarity

Natural variations

Alternative sequence241 – 417177Missing in isoform CD22-alpha.
Natural variant341A → T
Natural variant1521Q → E Observed with a marginally higher frequency in patients with systemic lupus erythematosus.
Natural variant2031E → K
Natural variant6391Y → H: dbSNP rs1058407.
Natural variant6641S → G
Natural variant6691R → C
Natural variant7451G → D

Experimental info

Sequence conflict4861A → R in CAA42006. Ref.1
Sequence conflict788 – 7892PD → RT in CAA42006. Ref.1

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Sequences

Sequence LengthMass (Da)Tools
Isoform CD22-beta [UniParc].

Last modified July 15, 1999. Version 2.
Checksum: 38EB0BE4220ACA2D

FASTA84795,348
        10         20         30         40         50         60 
MHLLGPWLLL LVLEYLAFSD SSKWVFEHPE TLYAWEGACV WIPCTYRALD GDLESFILFH 

        70         80         90        100        110        120 
NPEYNKNTSK FDGTRLYEST KDGKVPSEQK RVQFLGDKNK NCTLSIHPVH LNDSGQLGLR 

       130        140        150        160        170        180 
MESKTEKWME RIHLNVSERP FPPHIQLPPE IQESQEVTLT CLLNFSCYGY PIQLQWLLEG 

       190        200        210        220        230        240 
VPMRQAAVTS TSLTIKSVFT RSELKFSPQW SHHGKIVTCQ LQDADGKFLS NDTVQLNVKH 

       250        260        270        280        290        300 
TPKLEIKVTP SDAIVREGDS VTMTCEVSSS NPEYTTVSWL KDGTSLKKQN TFTLNLREVT 

       310        320        330        340        350        360 
KDQSGKYCCQ VSNDVGPGRS EEVFLQVQYA PEPSTVQILH SPAVEGSQVE FLCMSLANPL 

       370        380        390        400        410        420 
PTNYTWYHNG KEMQGRTEEK VHIPKILPWH AGTYSCVAEN ILGTGQRGPG AELDVQYPPK 

       430        440        450        460        470        480 
KVTTVIQNPM PIREGDTVTL SCNYNSSNPS VTRYEWKPHG AWEEPSLGVL KIQNVGWDNT 

       490        500        510        520        530        540 
TIACAACNSW CSWASPVALN VQYAPRDVRV RKIKPLSEIH SGNSVSLQCD FSSSHPKEVQ 

       550        560        570        580        590        600 
FFWEKNGRLL GKESQLNFDS ISPEDAGSYS CWVNNSIGQT ASKAWTLEVL YAPRRLRVSM 

       610        620        630        640        650        660 
SPGDQVMEGK SATLTCESDA NPPVSHYTWF DWNNQSLPYH SQKLRLEPVK VQHSGAYWCQ 

       670        680        690        700        710        720 
GTNSVGKGRS PLSTLTVYYS PETIGRRVAV GLGSCLAILI LAICGLKLQR RWKRTQSQQG 

       730        740        750        760        770        780 
LQENSSGQSF FVRNKKVRRA PLSEGPHSLG CYNPMMEDGI SYTTLRFPEM NIPRTGDAES 

       790        800        810        820        830        840 
SEMQRPPPDC DDTVTYSALH KRQVGDYENV IPDFPEDEGI HYSELIQFGV GERPQAQENV 


DYVILKH

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Isoform CD22-alpha [UniParc].

Checksum: 04F241A74FF61471
Show »

67075,799

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References

« Hide 'large scale' references
[1]"cDNA cloning of the B cell membrane protein CD22: a mediator of B-B cell interactions."
Wilson G.L., Fox C.H., Fauci A.S., Kehrl J.H.
J. Exp. Med. 173:137-146(1991) [PubMed: 1985119] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM CD22-BETA), VARIANT HIS-639.
Tissue: Tonsil.
[2]"Genomic structure and chromosomal mapping of the human CD22 gene."
Wilson G.L., Najfeld V., Kozlow E., Menniger J., Ward D., Kehrl J.H.
J. Immunol. 150:5013-5024(1993) [PubMed: 8496602] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE (ISOFORMS CD22-ALPHA AND CD22-BETA).
[3]"The B-cell antigen CD22 mediates monocyte and erythrocyte adhesion."
Stamenkovic I., Seed B.
Nature 345:74-77(1990) [PubMed: 1691828] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE (ISOFORM CD22-BETA).
[4]"The DNA sequence and biology of human chromosome 19."
Grimwood J., Gordon L.A., Olsen A.S., Terry A., Schmutz J., Lamerdin J.E., Hellsten U., Goodstein D., Couronne O., Tran-Gyamfi M., Aerts A., Altherr M., Ashworth L., Bajorek E., Black S., Branscomb E., Caenepeel S., Carrano A.V. expand/collapse author list , Caoile C., Chan Y.M., Christensen M., Cleland C.A., Copeland A., Dalin E., Dehal P., Denys M., Detter J.C., Escobar J., Flowers D., Fotopulos D., Garcia C., Georgescu A.M., Glavina T., Gomez M., Gonzales E., Groza M., Hammon N., Hawkins T., Haydu L., Ho I., Huang W., Israni S., Jett J., Kadner K., Kimball H., Kobayashi A., Larionov V., Leem S.-H., Lopez F., Lou Y., Lowry S., Malfatti S., Martinez D., McCready P.M., Medina C., Morgan J., Nelson K., Nolan M., Ovcharenko I., Pitluck S., Pollard M., Popkie A.P., Predki P., Quan G., Ramirez L., Rash S., Retterer J., Rodriguez A., Rogers S., Salamov A., Salazar A., She X., Smith D., Slezak T., Solovyev V., Thayer N., Tice H., Tsai M., Ustaszewska A., Vo N., Wagner M., Wheeler J., Wu K., Xie G., Yang J., Dubchak I., Furey T.S., DeJong P., Dickson M., Gordon D., Eichler E.E., Pennacchio L.A., Richardson P., Stubbs L., Rokhsar D.S., Myers R.M., Rubin E.M., Lucas S.M.
Nature 428:529-535(2004) [PubMed: 15057824] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
[5]"Identification of the gene variations in human CD22."
Hatta Y., Tsuchiya N., Matsushita M., Shiota M., Hagiwara K., Tokunaga K.
Immunogenetics 49:280-286(1999) [PubMed: 10079291] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 13-137; 139-239; 241-328 AND 418-502, VARIANTS THR-34; GLU-152; LYS-203; GLY-664; CYS-669 AND ASP-745.
[6]"Natural ligands of the B cell adhesion molecule CD22 beta carry N-linked oligosaccharides with alpha-2,6-linked sialic acids that are required for recognition."
Powell L.D., Sgroi D., Sjoberg E.R., Stamenkovic I., Varki A.
J. Biol. Chem. 268:7019-7027(1993) [PubMed: 8463235] [Abstract]
Cited for: SIALIC ACID-BINDING.
[7]"A role in B cell activation for CD22 and the protein tyrosine phosphatase SHP."
Doody G.M., Justement L.B., Delibrias C.C., Matthews R.J., Lin J., Thomas M.L., Fearon D.T.
Science 269:242-244(1995) [PubMed: 7618087] [Abstract]
Cited for: INTERACTION WITH PTPN6.
[8]"Involvement of p72syk kinase, p53/56lyn kinase and phosphatidyl inositol-3 kinase in signal transduction via the human B lymphocyte antigen CD22."
Tuscano J.M., Engel P., Tedder T.F., Agarwal A., Kehrl J.H.
Eur. J. Immunol. 26:1246-1252(1996) [PubMed: 8647200] [Abstract]
Cited for: INTERACTION WITH LYN; SYK AND PIK3R1/PIK3R2.
[9]"CD22 associates with protein tyrosine phosphatase 1C, Syk, and phospholipase C-gamma(1) upon B cell activation."
Law C.L., Sidorenko S.P., Chandran K.A., Zhao Z., Shen S.H., Fischer E.H., Clark E.A.
J. Exp. Med. 183:547-560(1996) [PubMed: 8627166] [Abstract]
Cited for: INTERACTION WITH PTPN6; SYK AND PLCG1.
[10]"CD22, a B lymphocyte-specific adhesion molecule that regulates antigen receptor signaling."
Tedder T.F., Tuscano J., Sato S., Kehrl J.H.
Annu. Rev. Immunol. 15:481-504(1997) [PubMed: 9143697] [Abstract]
Cited for: REVIEW.

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Cross-references

Sequence databases

X59350 mRNA. Translation: CAA42006.1.
X52785 mRNA. Translation: CAA36988.1. Frameshift.
U62631 Genomic DNA. Translation: AAB06448.1.
U62631 Genomic DNA. Translation: AAB06449.1.
AB012995 Genomic DNA. Translation: BAA36564.1.
AB012996 Genomic DNA. Translation: BAA36565.1.
AB012997 Genomic DNA. Translation: BAA36566.1.
AB012998 Genomic DNA. Translation: BAA36567.1.
AB012999 Genomic DNA. Translation: BAA36568.1.
AB013000 Genomic DNA. Translation: BAA36569.1.
AB013002 Genomic DNA. Translation: BAA36571.1.
AB013003 Genomic DNA. Translation: BAA36572.1.
AB013004 Genomic DNA. Translation: BAA36573.1.
AB013006 Genomic DNA. Translation: BAA36575.1.
PIRA35648.
RefSeqNP_001762.2.
UniGeneHs.643440

3D structure databases

ModBaseSearch...

Protein-protein interaction databases

IntActP20273.

PTM databases

PhosphoSiteP20273.

Genome annotation databases

EnsemblENSG00000012124. Homo sapiens. [Contig view]
GeneID933.
KEGGhsa:933.

Organism-specific databases

HGNCHGNC:1643. CD22.
HPACAB002418.
MIM107266. gene.
PharmGKBPA26201.
GenAtlas