Human SIGLEC2/CD22 Recombinant Protein (RPES4218)

Human SIGLEC2/CD22 Recombinant Protein

CD22 is a member of the immunoglobulin superfamily; SIGLEC family of lectins. It is first expressed in the cytoplasm of pro-B and pre-B cells; and on the surface as B cells mature to become IgD+. CD22 serves as an adhesion receptor for sialic acid-bearing ligands expressed on erythrocytes and all leukocyte classes. In addition to its potential role as a mediator of intercellular interactions; signal transduction through CD22 can activate B cells and modulate antigen receptor signaling in vitro. The phenotype of CD22-deficient mice suggests that CD22 is primarily involved in the generation of mature B cells within the bone marrow; blood; and marginal zones of lymphoid tissues. CD22 recruits the tyrosine phosphatase Src homology 2 domain-containing phosphatase 1 (SHP-1) to immunoreceptor tyrosine-based inhibitory motifs (ITIMs) and inhibits B-cell receptor (BCR)-induced Ca2+ signaling on normal B cells. CD22 interacts specifically with ligands carrying alpha2-6-linked sialic acids. As an inhibitory coreceptor of the B-cell receptor (BCR); CD22 plays a critical role in establishing signalling thresholds for B-cell activation. Like other coreceptors; the ability of CD22 to modulate B-cell signalling is critically dependent upon its proximity to the BCR; and this in turn is governed by the binding of its extracellular domain to alpha2;6-linked sialic acid ligands. However; genetic studies in mice reveal that some CD22 functions are regulated by ligand binding; whereas other functions are ligand-independent and may only require expression of an intact CD22 cytoplasmic domain at the B-cell surface. CD19 regulates CD22 phosphorylation by augmenting Lyn kinase activity; while CD22 inhibits CD19 phosphorylation via SHP-1.Immune Checkpoint   Immunotherapy   Cancer Immunotherapy   Targeted Therapy