Invitrogen™ Human Siglec-2 (CD22) His-tag Recombinant Protein

Catalog No.	Quantity
A42608	5 μg
A42609	50 μg

Catalog No. A42608 Supplier Invitrogen™ Supplier No. A42608

Description

Recombinant Protein

Reconstitution: Dissolve the protein in sterile double distilled water to a concentration of 0.2 mg/mL or lower. It is recommended that the protein be aliquoted and be used as soon as possible. Store aliquots under sterile conditions at -20°C. Avoid repeated freeze-thaw cycles.

CD22, also known as BL-CAM, is a type I transmembrane glycoprotein composed of two polypeptide chains, CD22alpha and CD22beta, with molecular weights of 130 and 140 kDa, respectively. These chains are produced by alternative splicing of the CD22 gene. CD22 is prominently expressed on mature B cells and B cell lymphomas, including hairy cell leukemia, diffuse large B-cell lymphoma, and nodular lymphocyte predominance Hodgkin's lymphoma, but is negative in classical Hodgkin's lymphoma. The extracellular portion of CD22 contains seven Ig-like domains that preferentially bind alpha2,6-linked sialic acid moieties found on epithelial, endothelial, B, and T cells. This binding can be masked by cis interactions with sialic acids on the same cell surface. CD22 expression is limited to late stages of B-cell differentiation, making it useful for phenotyping mature leukemias. Intracellularly, CD22 features six tyrosine residues within immunotyrosine-based inhibitory motifs (ITIM) and activation-like motifs. These residues are phosphorylated upon B-cell receptor engagement, allowing CD22 to regulate B-cell receptor signaling. CD22 participates in positive regulation through interactions with Src family tyrosine kinases and acts as an inhibitory receptor by recruiting cytoplasmic phosphatases via SH2 domains, which block signal transduction through dephosphorylation of signaling molecules. CD22's role in both positive and negative regulation of B-cell signaling, along with its specific expression pattern, makes it a valuable marker for antibody customers interested in B-cell-related research and diagnostics.

Specifications

• Accession Number: P20273
• For Use With (Application): Control, ELISA Standard, Binding Assay
• Formulation: PBS with 0.01% Tween 80, 5% mannitol, 5% trehalose and no preservative; pH 7.4
• Gene ID (Entrez): 933
• Molecular Weight (g/mol): 76.6 kDa
• Name: Human Siglec-2 (CD22) His-tag
• pH Range: 7.4
• Purification Method: Purified
• Quantity: 5 μg
• Source: HEK293 cells
• Storage Requirements: -20°C or -80°C if preferred
• Regulatory Status: RUO
• Endotoxin Concentration: <1.0 EU/μg
• Gene Alias: A530093D23; B-cell receptor CD22; BL-CAM; B-lymphocyte cell adhesion molecule; B-lymphocyte cell adhesion molecule (BL-CAM); Cd22; CD22 antigen; CD22 molecule; FLJ22814; Lectin 2; Leu-14; Lyb8; Lyb-8; MGC130020; sialic acid binding Ig-like lectin 2; sialic acid-binding Ig-like lectin 2; Sialic acid-binding Ig-like lectin 2 (Siglec-2); Siglec2; Siglec-2; T-cell surface antigen Leu-14
• Common Name: CD22
• Gene Symbol: CD22
• Biological Activity: Measured by its binding ability in a functional ELISA. Immobilized Human Siglec-2 (CD22) His-tag Recombinant Protein (at 0.02 μg/mL (100 uL/well) can bind anti-human CD22 Mab with a linear range of 0.2-50 ng/mL)
• Product Type: Protein
• Conjugate: Unconjugated
• Species: Human
• Recombinant: Recombinant
• Protein Tag: His-tag
• Sequence: Human CD22 isoform beta, amino acids Met1-Arg687 (Accession # P20273-1) with a C-terminal His-tag
• Content And Storage: Store at -20 to -70 °C
• Activity: Measured by its binding ability in a functional ELISA. Immobilized Human Siglec-2 (CD22) His-tag Recombinant Protein at 0.02 μg/mL (100uL/well) can bind anti-human CD22 Mab with a linear range of 0.2-50 ng/mL.
• Endotoxin Level: < 1 EU/μg
• Shipping Condition: Room Temperature
• Expression System: HEK293 cells
• Protein Family: CD Proteins
• Protein Form: Cell Surface Protein, Recombinant, Truncated
• Form: Lyophilized
• Protein Subtype: Lectins & Leptins
• Research Category: Immunology, Signal Transduction
• Purity or Quality Grade: ≥95 % as determined by SDS-PAGE. ≥90 % as determined by SEC-HPLC.
• Protein: CD22 molecule

Frequently Asked Questions (FAQs)

What is the relationship between specific activity units and International Units of activity?

There is no direct correlation or calculation between specific activity unit and International Unit (IU) values. International Units (IU) express a quantification of activity for the base amount of a substance in relation to an analogous reference standard with an internationally accepted unit of biological potency (i.e., IU/ng) that has been assigned based on an International Collaborative Study conducted by the World Health Organization (WHO). WHO Reference Standards are made available by the National Institute for Biological Standards and Control (NIBSC). Intended to simplify the comparison of activity of a substance obtained from different sources, IU measurements can vary as comparison methods are rarely the same between sources. A true direct comparison requires standardized methods of analysis in order to guarantee comparability of the substance’s activity in relation to its mass across sources.

Why can't I see the protein pellet in the vial for my lyophilized recombinant protein? Is this normal?

Gibco recombinant proteins are frequently formulated without carrier proteins or additives (e.g., BSA, HSA, sucrose, etc.) and Gibco PeproTech recombinant proteins don't contain a carrier protein. As a result, during lyophilization, the protein product may be deposited on the vial as a thin, and sometimes invisible film instead of a pellet. The size of the pellet, if any, is not directly related to the quantity of the recombinant protein in the vial. Our quality control procedures assure that each vial contains the correct amount of product.

To ensure complete recovery of protein product, before opening a vial of lyophilized recombinant protein, we recommend centrifuging it in a microcentrifuge for 20-30 seconds to drive any protein that may be lodged in the cap or on the side or the bottom of the vial. After reconstitution, you can confirm the presence of product protein by running a small amount on SDS-PAGE. In general, a protein band with expected size should be visible with as little as 10 ng of protein loaded on an acrylamide gel.

Does a particular recombinant protein contain the wild-type or mutated amino acid sequence?

Protein sequence information is available on the individual product page, except for proprietary engineered proteins.

What kind of tubes should I use for storing aliquots of reconstituted recombinant proteins?

In general, we recommend using polypropylene tubes for storing aliquots of reconstituted recombinant proteins. Specific information for appropriate storage and handling of many recombinant proteins can be found on the product pages.

Does each lot of recombinant protein have the same specific activity?

No, each lot can vary slightly with regards to its specific activity. The information on the data sheet for each product is provided as a guide. For lot-specific information, please please check the Certificate of Analysis or contact Technical Support.

What is the specific activity of my recombinant protein?

The ED50 for each functionally active recombinant protein can be found on its product page under Activity as well as in the data sheet. The specific activity (units/mg) for each recombinant protein can be determined from the ED50 using information available in our Tech Tip here: https://assets.thermofisher.com/TFS-Assets/BID/Technical-Notes/converting-ed50-ng-ml-specific-activity-units-mg-tech-note.pdf

What is the shelf life of your recombinant proteins?

The majority of our recombinant proteins have a guaranteed shelf life of one year unless otherwise indicated in our technical data sheets. This guarantee applies only if the recombinant protein is stored under the conditions stated in the data sheet. If you are not completely satisfied with the performance of the product, please contact Technical Support at techsupport@thermofisher.com for assistance.

Why is my recombinant protein not soluble?

The solubility issue might be due to improper handling, or use of a solvent other than the one we recommended. We recommend that you warm the lyophilized powder to room temperature before you open the vial, and that you solubilize the protein in the buffer solution recommended in the manual (some proteins are more soluble in low pH buffer). Do not reconstitute at a protein concentration greater than 1 mg/mL. Do not vortex or mix protein solutions vigorously. Allowing the reconstituted protein to incubate overnight at 4 degrees C may help resolve any solubility issues.

Are Thermo Fisher Scientific recombinant proteins calibrated with the WHO Reference Standard?

Where possible, Thermo Fisher Scientific obtains International Unit (IU) values through multiple side-by-side comparisons of our product(s) against the analogous WHO Reference Standard within our biological activity assay. Performing multiple comparison tests allows us to account for any outliers due to possible variations with the assay (e.g., product handling, assay protocol, etc.). Using the results of these comparisons, we can provide a reliable quantification of our product’s activity in relation to the activity of the WHO Reference Standard.

Information pertaining to whether a specific product has been tested against the WHO Reference Standard can typically be located on the product page or COA.

What are the major differences between the recombinant proteins produced in different expression systems?

The recombinant proteins provided by Thermo Fisher Scientific are usually produced in different expression systems such as E. coli, insect cells, or mammalian cells. The major differences in recombinant proteins produced in different expression systems are in the post-translational modifications present, such as glycosylation. Recombinant proteins produced in E. coli are not glycosylated. Recombinant proteins produced in insect cells are partially glycosylated without galactose and sialic acid and not branched. Recombinant proteins produced in mammalian cells are fully glycosylated.

Note: Mimic Sf9 Insect Cells (a derivative of the Sf9 insect cell line that has been modified to stably express a variety of mammalian glycosyltransferases) can be used for production of complex N-glycans with terminal sialic acid and galactose.

Why do I have to freeze recombinant protein solutions in working aliquots?

Repeated freeze/thaws will affect the stability of the recombinant protein. For example, freezing will significantly affect the pH of the protein solution and might cause denaturation of the protein (Arch Biochem Biophys 384:398 (2000)).