Recombinant Human Active Blk Protein, CF

  • Purity
    >70%, by SDS-PAGE under reducing conditions and visualized by Colloidal Coomassie® Blue stain at 5 μg per lane
  • Activity
    The activity of Blk is typically 95-129 nmol/min/mg using a poly (Glu:Tyr, 4:1) synthetic peptide substrate (see Activity Assay Protocol).
  • Source
    Spodoptera frugiperda, Sf 9 (baculovirus)-derived Accession # BC_007371
  • Accession #
  • N-terminal Sequence
    Using an N terminal GST tag
  • Predicted Molecular Mass
    84 kDa
Formulation Supplied in 50 mM Tris-HCl (pH 7.5), 150 mM NaCl, 0.25 mM DTT, 10 mM glutathione, 0.1 mM EDTA, 0.1 mM PMSF, and 25% glycerol.
Shipping The product is shipped with dry ice or equivalent. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: This product is stable at ≤ ‑70° C for up to 1 year from the date of receipt. For optimal storage, aliquot into smaller quantities after centrifugation and store at recommended temperature. Avoid repeated freeze-thaw cycles.
Assay Procedure
  • Active Kinase - Active Blk (0.1 μg/μL) diluted with Kinase Dilution Buffer. Note: These are suggested working dilutions. Optimal dilutions should be determined by each laboratory for each application.
  • Kinase Assay Buffer II, pH 7.2 - 25 mM MOPS, 12.5 mM beta -glycerolphosphate, 20 mM MgCl2, 25 mM MnCl2, 5 mM EGTA, 2 mM EDTA. Add 0.25 mM DTT to the Kinase Assay Buffer prior to use.
  • Kinase Dilution Buffer, pH 7.2 - Kinase Assay Buffer II diluted 5-fold with distilled or deionized water.
  • 10 mM ATP Stock Solution - Prepare the ATP Stock Solution by dissolving 55 mg of ATP in 10 mL of Kinase Assay Buffer II. Store 200 μL aliquots at ≤ -20 °C.
  • [32P]-ATP Assay Cocktail - Prepare 250 μM [32P]-ATP Assay Cocktail in a designated radioactive work area by combining 150 μL of 10 mM ATP Stock Solution, 100 μL of [32P]-ATP (1 mCi/100 μL), and 5.75 mL of Kinase Assay Buffer II. Store 1 mL aliquots
    at ≤ -20 °C.
  • Substrate - Poly (Glu:Tyr; 4:1) synthetic peptide was diluted in distilled or deionized water to a final concentration of 1 mg/mL.
  1. Thaw the [32P]-ATP Assay Cocktail in a shielded container in a designated radioactive work area.
  2. Thaw the Active Blk, Kinase Assay Buffer II, Substrate, and Kinase Dilution Buffer on ice.
  3. In a pre-cooled microfuge tube, add the following reaction components bringing the initial reaction volume up to 20 μL.
    a. Diluted Active Blk: 10 μL
    b. Poly Substrate (1 mg/mL on ice): 10 μL
  4. Set up the blank control as outlined in step 3, excluding the addition of the substrate. Replace the substrate with an equal volume of distilled or deionized water.
  5. Initiate the reaction with the addition of 5 μL [32P]-ATP Assay Cocktail, bringing the final volume up to 25 μL. Incubate the mixture in a water bath at 30 °C for 15 minutes.
  6. After the 15 minute incubation, terminate the reaction by spotting 20 μL of the reaction mixture onto individual pre-cut strips of phosphocellulose P81 paper.
  7. Air dry the pre-cut P81 strip and sequentially wash in a 1% phosphoric acid solution (add 10 mL of phosphoric acid to 990 mL of distilled or deionized water) with constant gentle stirring. It is recommended that the strips be washed a total of three times for approximately 10 minutes each.
  8. Count the radioactivity on the P81 paper in the presence of scintillation fluid in a scintillation counter
  9. Determine the corrected cpm by subtracting the blank control value (see step 4) for each sample and calculate the kinase specific activity as outlined below:

    Calculation of [32P]-ATP Specific Activity (SA) (cpm/pmol)
    Specific Activity (SA) = cpm for 5 μL [32P]-ATP/pmol of ATP (in 5 μL of a 250 μM ATP stock solution; i.e. 1250 pmol)

    Calculation of Kinase Specific Activity (SA) (pmol/minutes/μg or nmol/minutes/mg)
    Corrected cpm from reaction / [(SA of 32P-ATP in cpm/pmol) x (Reaction time in minutes) x (Enzyme amount in μg or mg)] x [(Reaction volume) / (Spot Volume)]
Data Images
The approximate molecular weight is 84 kDa and the average purity is 90%.
Background: Blk
Blk, also known as B lymphoid kinase, is a 55 kDa tyrosine kinase with SH3, SH2, and catalytic domains that contain consensus sequences of the Src protein tyrosine kinase family. Blk is expressed specifically in the B cell lineage and plays a role in the signal transduction pathway that is restricted to B lymphoid cells (1). Stimulation of resting B-lymphocytes with antibodies to surface immunoglobulin (sIgD or sIgM) induces activation of Blk (2).
  • References:
    1.  Dymecki, S.M. et al. (1990) Science 247:332.
    2. Burkhardt, A.L. et al. (1991) Proc. Natl. Acad. Sci. USA 88:7410.
  • Long Name:
    B Lymphoid Tyrosine Kinase
  • Entrez Gene IDs:
    640 (Human); 12124 (Mouse); 364403 (Rat)
  • Alternate Names:
    B lymphocyte kinase; B lymphoid tyrosine kinase; BLK nonreceptor tyrosine kinase; Blk; EC; MGC10442; MODY11; p55-Blk; tyrosine-protein kinase Blk
Related Research Areas

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