General Notes
This product (Catalog No. CPBT-51908RH) is a rabbit-derived polyclonal antibody raised against human CD22, targeting the amino acid region 176–330 of the protein. It has been affinity purified by Protein A. CD22, also known as Siglec-2, is a B-cell-restricted transmembrane glycoprotein that serves as an inhibitory receptor modulating B-cell receptor (BCR) signaling to regulate humoral immunity and prevent excessive B-cell activation. Structurally, CD22 is a type I membrane protein with a molecular weight of approximately 140 kDa, featuring seven extracellular immunoglobulin-like domains—the most membrane-distal of which (domain 1) is a V-set domain responsible for ligand binding—an intracellular tail with three immunoreceptor tyrosine-based inhibitory motifs (ITIMs) containing six tyrosine residues, and 12 N-linked glycosylation sites that influence its function and interactions. Expression of CD22 begins in the cytoplasm of early B-cell precursors, appears on the surface of mature B cells where it reaches maximal levels, and is downregulated on plasma cells, making it a hallmark marker of mature B lymphocytes across species including humans and mice. Functionally, CD22 binds specifically to α2,6-linked sialic acid residues on glycoproteins such as surface IgM (sIgM) and CD45 in cis (on the same cell) or in trans (on adjacent cells like T cells or endothelial cells), which triggers tyrosine phosphorylation of its ITIMs and recruitment of the phosphatase SHP-1 to dephosphorylate BCR signaling molecules, thereby dampening calcium mobilization, proliferation, and cytokine production in response to antigens or innate signals. This inhibitory role is essential for establishing B-cell signaling thresholds, maintaining peripheral B-cell tolerance, and averting autoimmunity, as evidenced by hyperresponsive B cells and increased autoantibody production in CD22-deficient mice.
CPBT-51908RH is suitable for use in ELISA (1:4,000–1:8,000), IHC (1:50–1:100), Western blot (WB) (1:1,000–1:4,000) applications.
CPBT-51908RH is supplied as a liquid formulation in 0.01M PBS, pH 7.4, 50% Glycerol, 0.05% Proclin 300. For long-term storage, keep at −20 °C. For short-term use, store at 2–8 °C. Avoid repeated freeze–thaw cycles to maintain antibody integrity and performance.
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