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  • Protein Phosphatase Inhibitor 2 (I-2)


    Protein Phosphatase Inhibitor-2 (I-2) specifically and instantaneously inhibits the catalytic subunit of type I protein phosphatase (PP1) at nanomolar concentrations. In contrast, the inhibition of native forms of PP1, type 1 holoenzymes, is time dependent and requires much more I-2. I-2 inhibits PP1 from mammals, yeast and flies in an identical manner and can be used for identification of type I protein phosphatases from many different species (1-3).

    I-2 is a 204 amino acid heat stable protein. Recombinant I-2 has identical inhibitory properties as native rabbit muscle I-2 (2).

    I-2 is functionally tested in the inhibition assays of PP1 (NEB #P0754).


  • Type 1 protein phosphatase (PP1) specific Inhibitor
  • Rabbit skeletal muscle, recombinant (E. coli)
  • Supplied with 10X Reaction Buffer
  • Product Source

    Isolated from a strain of E. coli that carries the coding sequence for rabbit skeletal muscle I-2 polypeptide under the control of T7 expression system (kindly provided by Dr. A. A. DePaoli-Roach) (3).

    Properties and Usage

    Storage Temperature


    Storage Conditions

    50 mM HEPES
    50% Glycerol
    0.01% Brij 35
    0.1 mM EGTA
    pH 7.0 @ 25°C

    Molecular Weights

    Apparent: 31 kDa
    Theoretical: 22.8 kDa

    Shipping Notes

    • Ships on dry ice

    Quality Control

    Quality Assurance Statement

    • Free of detectable protease and phosphatase activity.

    Quality Control Assays

    The following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page.
    • Phosphatase Activity (PNPP):
      The product is tested in a reaction containing a p-nitrophenyl phosphate (PNPP), a chromogenic substrate for most phosphatases. After incubation there is no detectable phosphatase activity as determined by spectrophotometric analysis of released p-nitrophenol at 405 nm.
    • Protease Activity (SDS-PAGE):

      The product is tested for protease activity by incubation with a standard mixture of proteins resulting in no detectable degradation of the proteins as determined by SDS-PAGE.


    1. PP1 or cell extracts should be diluted so that the concentration of phosphatase activity is less than 0.1 U/ml in the assays. One unit is the amount of PP1 that hydrolyzes 1 nmol of substrate in 1 minute. The diluted extracts must be preincubated with I-2 for 10-15 minutes prior to assay in order to achieve complete inhibition (1).
    2. I-2 has been purified to > 95% homogeneity as determined by SDS-PAGE and Coomassie Blue staining.
    3. Recommended long term storage -70°C; avoid repeated freeze/thaw cycles.


    1. Cohen, P. (1991). Methods in Enzymology. 201, 389-398.
    2. Park, I., et al. (1994). J. Biol. Chem. 269, 944-954.
    3. Connor, J.H., et al. (2000). J. Biol. Chem. 275, 18670-18675.

    Supporting Documents

    Material Safety Datasheets

    The following is a list of Material Safety Data Sheets (MSDS) that apply to this product to help you use it safely. The following file naming structure is used to name these document files: [Product Name] MSDS. For international versions please contact us at info@neb.com.


    The Product Summary Sheet, or Data Card, includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name the majority of these document files: [Catalog Number]Datasheet-Lot[Lot Number]. For those product lots not listed below, please contact NEB at info@neb.com or fill out the Technical Support Form for appropriate document.