CD22 Protein Overview: Sequence, Structure, Function and Protein Interaction

CD22 Protein Overview

The human B-lymphocyte-restricted antigen CD22 is expressed early in B-cell development in pro-B cells, as a cytoplasmic protein, and later in B-cell development, at the late pre-B-cell stage, as a cell surface protein. Once expressed as a membrane protein, CD22 persists on B cells until they differentiate into plasma cells. The presence of cytoplasmic CD22 is a useful marker for B-cell precursor acute lymphocytic leukemia. CD22 appears to be a heterodimer consisting of 130- and 140-kD glycoproteins with protein cores of 80 and 100 kD, respectively. The 2 subunits are thought to be independently transported to the surface and originate from 2 separate precursor molecules. Studies of the structure of the 2 proteins and cDNA cloning suggested that the 2 proteins arise from differential RNA processing of the same gene, with the larger subunit being composed of an extracellular portion of 7 immunoglobulin domains, 1 V-like and 6 C-like, and a smaller subunit of 5 Ig domains, 1 V-like and 4 C-like. The CD22 polypeptide is structurally related to myelin-associated glycoprotein (MAG; 159460), neural cell adhesion molecule (NCAM; 116930), and carcinoembryonic antigen (CEA; 114890). Consistent with the structural similarities to the adhesion molecules, CD22 participates in adhesion between B cells and other cell types. Wilson et al. (1991) cloned a full-length cDNA corresponding to the B-cell membrane protein CD22.

CD22 protein family

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

CD22 protein name

Recommended name
B-cell receptor CD22
sialic acid binding Ig-like lectin 2, SIGLEC2, SIGLEC-2
Alternative name
B-lymphocyte cell adhesion molecule BL-CAM Sialic acid-binding Ig-like lectin 2 Siglec-2 T-cell surface antigen Leu-14 CD antigen CD22

CD22 Gene family protein

CD22 Protein Sequence

Species Human CD22 protein
Length 847
Mass (Da) 95348
Sequence Human CD22 protein sequence
Species Mouse CD22 protein
Length 862
Mass (Da) 96582
Sequence Mouse CD22 protein sequence
Mass (Da)

CD22 Protein Molecular Weight & PI

B-cell receptor CD22 precursor (B-lymphocyte cell adhesion molecule) (BL-CAM) (Sialic acid-binding Ig-like lectin 2) (Siglec-2) (T-cell surface antigen Leu-14) (CD22 antigen) Homo sapiens (Human).

The parameters have been computed for the following feature

FT CHAIN 20-847 B-cell receptor CD22.

Molecular weight (Da)


Theoretical pI


CD22 Protein Structure

Crystal structure of human CD22 Ig domains 1-3
2017-04-21   Released:  2017-10-04
Deposition Author(s)
Julien, J.P., Ereno-Orbea, J., Sicard, T.
Homo sapiens
Expression System
Homo sapiens
Experimental Data Snapshot
2.1200 Å
R-Value Free
R-Value Work

Human CD22 protein Secondary structure

CD22 Protein Interaction

Recombinant CD22 Protein Feature

CD22 Protein, Human, Recombinant (His Tag)

High Purity
> 95 % as determined by SDS-PAGE
Low Endotoxin
< 1.0 EU per μg of the protein as determined by the LAL method
High Activity
Measured by its binding ability in a functional ELISA. Immobilized human CD22 (Cat:11958-H08H) at 0.02 μg/ml (100uL/well) can bind anti-human CD22 Mab with a linear range of 0.2-50 ng/ml.

Recombinant CD22 protein citations

Antibody Specific for CD22 and Methods of Use Thereof
D Rabuka, RGE Holgate, FJ Carr
US 20140161870 A1
Chimeric antigen receptors that trigger phagocytosis
Morrissey, M;Williamson, A;Steinbach, A;Roberts, E;Kern, N;Headley, M;Vale, R;

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