CD22 is a 130-140 kDa, single-pass type I transmembrane protein belonging to the immunoglobulin superfamily (IgSF) and sialic acid binding Ig-like lectin (SIGLEC) family. CD22 or SIGLEC2 contains 1 Ig-like V-type and 6 Ig-like C2-type domain in the extracellular region that specifically interacts with ligands carrying α2-6-linked sialic acids. Alternate splicing generates an additional isoform that lacks the 3rd and 4th Ig-like domains. CD22 is expressed on B cells and capable of modulating B cell antigen receptor (BCR)-mediated signals, as well as the generation of BCR-independent signals. CD22 is an inhibitory co-receptor of BCR and plays a critical role in establishing signalling thresholds for B-cell activation.  CD22 has 3 immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in its cytoplasmic region that recruits the tyrosine phosphatase Src homology 2 domain-containing phosphatase 1 (SHP-1) to ITIMs and inhibits BCR-induced Ca2+ signaling in B cells. Phosphorylation of Tyr822 within one of ITIMs is important for CD22 signal transduction through its association with the kinases Lyn, PI3-Kinase p85α, and SYK. Interaction of CD22 to ligands in trans can regulate B-cell migration as well as the BCR signaling threshold. A more complex role for CD22 has recently been described including a role in a regulatory loop that mediates basal signaling thresholds and Src-family protein tyrosine kinase (PTK) amplification after BCR ligation. CD19 regulates CD22 phosphorylation by augmenting Lyn kinase activity, while CD22 inhibits CD19 phosphorylation via SHP-1. 

CD22 is a 130-140 kDa, single-pass type I transmembrane protein belonging to the immunoglobulin superfamily (IgSF) and sialic acid binding Ig-like lectin (SIGLEC) family. CD22 or SIGLEC2 contains 1 Ig-like V-type and 6 Ig-like C2-type domain in the extracellular region that specifically interacts with ligands carrying α2-6-linked sialic acids. Alternate splicing generates an additional isoform that lacks the 3rd and 4th Ig-like domains. CD22 is expressed on B cells and capable of modulating B cell antigen receptor (BCR)-mediated signals, as well as the generation of BCR-independent signals. CD22 is an inhibitory co-receptor of BCR and plays a critical role in establishing signalling thresholds for B-cell activation.  CD22 has 3 immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in its cytoplasmic region that recruits the tyrosine phosphatase Src homology 2 domain-containing phosphatase 1 (SHP-1) to ITIMs and inhibits BCR-induced Ca2+ signaling in B cells. Phosphorylation of Tyr822 within one of ITIMs is important for CD22 signal transduction through its association with the kinases Lyn, PI3-Kinase p85α, and SYK. Interaction of CD22 to ligands in trans can regulate B-cell migration as well as the BCR signaling threshold. A more complex role for CD22 has recently been described including a role in a regulatory loop that mediates basal signaling thresholds and Src-family protein tyrosine kinase (PTK) amplification after BCR ligation. CD19 regulates CD22 phosphorylation by augmenting Lyn kinase activity, while CD22 inhibits CD19 phosphorylation via SHP-1. 

 

Product Details

 

Gene Symbol: CD22; SIGLEC2; SIGLEC-2; BL-CAM; Leu-14

 

NCBI Gene ID: 933

 

Uniprot Entry: P20273

 

Construct Details: The recombinant human CD22 ECD is expressed as a 675 amino acid protein consisting of Asp20 - Thr683 region of CD22 (UniProt accession #P20273) and a C-terminal His-tag. It contains 12 potential sites for N-linked glycosylation.

 

Source: Human cells stably expressing human CD22 ECD and growing in chemical-defined media with no animal components or antibiotics

 

Deduced Amino Acid Sequence:

DSSKWVFEHPETLYAWEGACVWIPCTYRALDGDLESFILFHNPEYNKNTSKFDGTRLYESTKDGKVPSEQKRVQFLGDKNKN

CTLSIHPVHLNDSGQLGLRMESKTEKWMERIHLNVSERPFPPHIQLPPEIQESQEVTLTCLLNFSCYGYPIQLQWLLEGVPM

RQAAVTSTSLTIKSVFTRSELKFSPQWSHHGKIVTCQLQDADGKFLSNDTVQLNVKHTPKLEIKVTPSDAIVREGDSVTMTC

EVSSSNPEYTTVSWLKDGTSLKKQNTFTLNLREVTKDQSGKYCCQVSNDVGPGRSEEVFLQVQYAPEPSTVQILHSPAVEGS

QVEFLCMSLANPLPTNYTWYHNGKEMQGRTEEKVHIPKILPWHAGTYSCVAENILGTGQRGPGAELDVQYPPKKVTTVIQNP

MPIREGDTVTLSCNYNSSNPSVTRYEWKPHGAWEEPSLGVLKIQNVGWDNTTIACAACNSWCSWASPVALNVQYAPRDVRVR

KIKPLSEIHSGNSVSLQCDFSSSHPKEVQFFWEKNGRLLGKESQLNFDSISPEDAGSYSCWVNNSIGQTASKAWTLEVLYAP

RRLRVSMSPGDQVMEGKSATLTCESDANPPVSHYTWFDWNNQSLPYHSQKLRLEPVKVQHSGAYWCQGTNSVGKGRSPLSTL

TVYYSPETSTGHHHHHHHH

 

M.W.: Calculated molecular mass (kDa): 76.0; Estimated by SDS-PAGE under reducing condition (kDa): 100-110 probably due to glycosylation

 

Calculated PI: 6.47

 

Calculated extinction coefficients (M-1 cm-1, at 280nm):  145395

 

Purity: >90% judged by SDS-PAGE under reducing condition (see the gel image above, labeled as "S" and "M" for marker)

 

Formulation: Supplied at 0.5 mg/ml in sterile PBS pH7.4 (carrier & preservative free).

 

Endotoxin Level: <0.1 EU per 1 μg of purified recombinant protein determined by the LAL method

 

Biological Activity: Immobilized CD22 ECD protein supports the adhesion of human red blood cells.  Binds anti-CD22 monoclonal antibodies (SKU#MAB1175, SKU#MAB1195) with high affinity (K_D < 5 nM) by ELISA.

 

  

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

Restriction: This product is not transferable or re-sellable.  Customer obtain no right to transfer, assign, or sublicense its use rights, or to transfer, resell, package, or otherwise distribute the product, or to use the product for the benefit of any third party or for any commercial purpose.  Customer may only use the product in compliance with applicable local, state and federal laws, regulations and rules.  Customer may not directly or indirectly use the product or allow the transfer, transmission, export or re-export of all or any part of the product in violation of any export control law or regulation of the united states or any other relevant jurisdiction.  Your use of this product constitutes acceptance of the terms of this limited use agreement.  Please refer to our “terms & conditions” for details.  If you are not willing to accept the limitation of this agreement, G&P Biosciences will accept return of the product for a full/partial refund.

 

Storage

 

The product is shipped at 4°C. Upon receipt, centrifuge the product briefly before opening the vial. It is recommended to store small aliquots at the temperature below –20°C for long-term storage and the product is stable for 3 months. The undiluted protein can be stored at 4°C for no more than 2 weeks.

 

 

Use a manual defrost freezer and avoid repeated freeze-thaw cycles.

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

 

References

 

1. Nature 345:74-77(1990)

2. J. Exp. Med. 173:137-146(1991)

3. Science 269:242-244(1995)

4. Annu. Rev. Immunol. 15:481-504(1997)

5. Immunol Rev. 230: 128-43 (2009)

 

 

Documentation

 

Product datasheet (pdf) can be downloaded here: FCL1015-PDS.pdf

 

 

 

Additional supporting documents, including COA and MSDS are available upon request.

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

Restriction: This product is not transferable or re-sellable.  Customer obtain no right to transfer, assign, or sublicense its use rights, or to transfer, resell, package, or otherwise distribute the product, or to use the product for the benefit of any third party or for any commercial purpose.  Customer may only use the product in compliance with applicable local, state and federal laws, regulations and rules.  Customer may not directly or indirectly use the product or allow the transfer, transmission, export or re-export of all or any part of the product in violation of any export control law or regulation of the united states or any other relevant jurisdiction.  Your use of this product constitutes acceptance of the terms of this limited use agreement.  Please refer to our “terms & conditions” for details.  If you are not willing to accept the limitation of this agreement, G&P Biosciences will accept return of the product for a full/partial refund.