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Recombinant Human Siglec-2/CD22 His-tag Protein, CF

Bio-Techne includes R&D Systems | Catalog # 10191-SL

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Product Specifications


Chinese Hamster Ovary cell line, CHO-derived human Siglec-2/CD22 protein
Asp20-Arg687, with a C-terminal 6-His tag


>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

Endotoxin Level

<0.10 EU per 1 μg of the protein by the LAL method.

N-terminal Sequence Analysis


Predicted Molecular Mass

76 kDa


110-130 kDa, under reducing conditions


Measured by the ability of the immobilized protein to support the adhesion of human red blood cells. Kelm, S. et al. (1994) Current Biology 4:965.
The ED50 for this effect is 0.05-0.6 μg/mL.

Scientific Data Images for Recombinant Human Siglec-2/CD22 His-tag Protein, CF

Recombinant Human Siglec-2/CD22 His-tag Protein Bioactivity

Recombinant Human Siglec-2/CD22 His-tag Protein Bioactivity

Recombinant Human Siglec-2/CD22 His-tag (Catalog # 10191-SL) supports the adhesion of human red blood cells. The ED50 for this effect is 0.05‑0.6 μg/mL.
Recombinant Human Siglec-2/CD22 His-tag Protein SDS-PAGE

Recombinant Human Siglec-2/CD22 His-tag Protein SDS-PAGE

2 μg/lane of Recombinant Human Siglec-2/CD22 His-tag (Catalog # 10191-SL) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® blue staining, showing bands at 110-130 kDa.

Formulation, Preparation and Storage

Formulation Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitution Reconstitute at 500 μg/mL in PBS.
Shipping The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.

Background: Siglec-2/CD22

Siglecs are type I transmembrane proteins that belong to the immunoglobulin (Ig) superfamily and function as mammalian lectins (1). They are characterized by an extracellular domain consisting of various numbers of Ig domains with a conserved N-terminal V-set Ig ligand-binding domain. This binds species-specific sialic acid motifs on protein and lipid scaffolds to regulate intracellular signaling pathways (2). The cytoplasmic tail has signaling motifs, in most cases immunoreceptor tyrosine-based inhibitory motif (ITIM) (3). Human Siglec-2, also known as B cell antigen CD22 or B lymphocyte cell adhesion molecule (BL-CAM), is a B cell restricted glycoprotein that is expressed in the cytoplasm of progenitor B and pre B cells and on the surface of mature B cells. Two distinct human Siglec-2/CD22 cDNAs that arise from differential RNA processing of the same gene have been isolated. The predominant Siglec-2/CD22 beta encodes an 847 amino acid (aa) polypeptide with a hydrophobic signal peptide, an N-terminal Ig-like V type domain, six Ig-like C2 type domains, a transmembrane region and a cytoplasmic tail with 4 immunoreceptor tyrosine-based inhibition motifs (ITIMs) (4). The variant Siglec-2/CD22 alpha encodes a 647 aa polypeptide missing two Ig-like C2 type domains and has a truncated (23 aa) cytoplasmic tail (5). Mature human Siglec-2 beta consists of a 668 amino acid (aa) extracellular domain (ECD), a 19 aa transmembrane segment, and a 141 aa cytoplasmic domain. Within the ECD, human Siglec-2 shares 59% and 58% aa sequence identity with the mouse and rat Siglec-2, respectively. Siglec-2/CD22 is an adhesion molecule that preferentially binds alpha 2,6- linked sialic acid on the same (cis) or adjacent (trans) cells. Interaction of CD22 with trans ligands on opposing cells was found to be favored over the binding of ligands in cis (6). Besides its role as an adhesion molecule, Siglec-2/CD22 is a coreceptor that physically interacts with B-cell receptor (BCR) and is rapidly phosphorylated upon BCR ligation. It negatively regulates BCR signals by recruiting tyrosine phosphatase SHP-1 to its ITIMs. Phosphorylated Siglec-2/CD22 can also interact with other intracellular effector proteins such as Syk, PLC gamma, PI3 kinase and Grb-2, suggesting it may play a role in positive signaling (7-9). Another function of CD22 is that it mediates the anti-phagocytic effect of alpha2,6-linked sialic acid, and inhibition of CD22 promotes the clearance of myelin debris, amyloid-beta oligomers and alpha-synuclein fibrils in vivo(10). CD22 also plays a role in autoimmunity and has great potential for CD22-based immunotherapeutics for the treatment of autoimmune diseases such as systemic lupus erythematosus (SLE) (11).


  1. Crocker, P.R. et al. (2007) Nat. Rev. Immunol. 7:255.
  2. Poe, J.C. and T.F. Tedder (2012) Trends Immunol. 33:413.
  3. Meyer, S.J. et al. (2018) Front. Immunol. 9:2820.
  4. Wilson, G.L et al. (1991) J. Exp. Med. 173:137.
  5. Stamenkovic, I. and B. Seed (1990) Nature 345:74.
  6. Collins, B.E. et al. (2004) Proc. Natl. Acad. Sci. 101:6104.
  7. Crocker, P.R. and A. Varki (2001) Immunology 103:137.
  8. Ravetch, J.V. and L.L. Lanier (2000) Science 290:84.
  9. Wienands, Y.J. et al. (1999) J. Biol. Chem. 274:18769.
  10. Pluvinage, J.V. et al. (2019) Nature. 5568:7751.
  11. Clark, E.A. et al. (2018) Front. Immunol. 9:2235.

Long Name

Sialic Acid Binding Ig-like Lectin 2

Alternate Names

BL-CAM, CD22, Siglec2

Entrez Gene IDs

933 (Human); 12483 (Mouse); 308501 (Rat); 102130968 (Cynomolgus Monkey)

Gene Symbol



Additional Siglec-2/CD22 Products

Product Documents for Recombinant Human Siglec-2/CD22 His-tag Protein, CF

Certificate of Analysis

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Product Specific Notices for Recombinant Human Siglec-2/CD22 His-tag Protein, CF

For research use only