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Human Siglec-2 / CD22 HEK293 Cell Lysate (WB positive control)

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Human CD22 Transfected / Overexpression Cell Lysate Product Information
Expressed Host:Human Cells
Product Description:Human Cell lysate that Human Siglec-2 / CD22 transfected / overexpressed for Western blot (WB) positive control. The whole cell lysate is provided in 1X Sample Buffer (1X modified RIPA buffer+1X SDS loading buffer).
Sequence information:A DNA sequence encoding the human CD22 isoform-beta (P20273-1) extracellular domain (Met 1-Arg 687) was fused with a polyhistidine tag at the C-terminus.
Predicted N Terminal:Asp 20
Molecule Mass:The recombinant human CD22 consists of 679 amino acids and predictes a molecular mass of 76.6 kDa. In SDS-PAGE under reducing conditions, the apparent molecular mass of rhCD22 is approximately 120-130 kDa due to glycosylation.
Human CD22 Transfected / Overexpression Cell Lysate Usage Guide
Preparation Method:Cell lysate was prepared by homogenization in ice-cold modified RIPA Lysis Buffer with cocktail of protease inhibitors (Sigma). Cell debris was removed by centrifugation. Protein concentration was determined by Bradford assay (Bio-Rad protein assay, Microplate Standard assay). The cell lysate was boiled for 5 min in 1 x SDS loading buffer (50 mM Tris-HCl pH 6.8, 12.5% glycerol, 1% sodium dodecylsulfate, 0.01% bromophenol blue) containing 5% b-mercaptoethanol, and lyophilized.
Lysis Buffer:Modified RIPA Lysis Buffer: 50 mM Tris-HCl pH 7.4, 150 mM NaCl, 1mM EDTA, 1% Triton X-100, 0.1% SDS, 1% Sodium deoxycholate, 1mM PMSF.
Quality Control Testing:12.5% SDS-PAGE Stained with Coomassie Blue after protein purification.
Stability:Samples are stable for up to twelve months from date of receipt.
Recommend Usage:1.  Centrifuge the tube for a few seconds and ensure the pellet at the bottom of the tube. 2.  Re-dissolve the pellet using 200μL pure water and boil for 2-5 min. 3. Store the lyophilized cell lysate at 4℃. After re-dissolution, recommend to aliquot it into smaller quantities and store at -80℃.
Storage Buffer:1 X Sample Buffer (1 X modified RIPA buffer+1 X SDS loading buffer).
Storage Instruction:Store at 4℃. After re-dissolution, aliquot and store at -80℃.
Application notes:Western blot (WB): Use at an assay dependent dilution.
Other Applications: Not tested.
Optimal dilutions/concentrations should be determined by the end user.
CD22 Background

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.

Human CD22 References
  • Tedder TF, et al. (1997) CD22, a B lymphocyte-specific adhesion molecule that regulates antigen receptor signaling. Annu Rev Immunol. 15: 481-504.
  • Tedder TF, et al. (2005) CD22: a multifunctional receptor that regulates B lymphocyte survival and signal transduction. Adv Immunol. 88: 1-50.
  • Fujimoto M, et al. (2007) B cell signaling and autoimmune diseases: CD19/CD22 loop as a B cell signaling device to regulate the balance of autoimmunity. J Dermatol Sci. 46(1): 1-9.
  • Walker JA, et al. (2008) CD22: an inhibitory enigma. Immunology. 123(3): 314-25.
  • Nitschke L. (2009) CD22 and Siglec-G: B-cell inhibitory receptors with distinct functions. Immunol Rev. 230(1): 128-43.
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    Catalog: 11958-H08HL-300
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