Human Siglec-2/CD22 LlamabodyTM VHH His-tag Antibody
Human Siglec-2/CD22 LlamabodyTM VHH His-tag Antibody Summary
Please Note: Optimal dilutions should be determined by each laboratory for each application. General Protocols are available in the Technical Information section on our website.
Detection of Siglec-2/CD22 in HEK293 Human Cell Line Transfected with Human Siglec-2/CD22 and eGFP by Flow Cytometry. HEK293 human embryonic kidney cell line transfected with either (A) human Siglec-2/CD22 or (B) irrelevant protein and eGFP was stained with Llama Anti-Human Siglec-2/CD22 Llamabody VHH Monoclonal Antibody (Catalog # LMAB10732) followed by Goat Anti-Llama Secondary Antibody (AF011), and then Allophycocyanin-conjugated Anti-Goat IgG Tertiary Antibody (F0108). Quadrant markers were set based on secondary plus tertiary antibody staining in the absence of primary antibody. View our protocol for Staining Membrane-associated Proteins.
Detection of Siglec‑2/CD22 in Transfected HEK293 Cell Line (Positive) And Wild Type HEK293Cell Line (Negative) Cells. Siglec‑2/CD22 was detected in immersion fixed Transfected HEK293 Human Embryonic Kidney Cell Line (Positive) and absent in Wild Type HEK293 Human Embryonic Kidney Cell Line (Negative) Cells using Llama Anti-Human Siglec‑2/CD22 LlamabodyTM VHH His-tag Monoclonal Antibody (Catalog # LMAB10732) at 5 µg/mL for 3 hours at room temperature. Cells were stained using Anti-camelid Vhh conjugated to Rhodamine-Red X (red) and counterstained with DAPI (blue). Specific staining was localized to cytoplasm. View our protocol for Fluorescent ICC Staining of Cells on Coverslips.
Preparation and Storage
- 12 months from date of receipt, -20 to -70 °C as supplied.
- 1 month, 2 to 8 °C under sterile conditions after reconstitution.
- 6 months, -20 to -70 °C under sterile conditions after reconstitution.
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 alpha 2,6-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).
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Why is the Llamabody antibody called VHH His-tag? Does it detect His?
No, the antibody does not cross-react with His. It has a His-tag which is used for purification of the recombinant antibody.
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