• Product name

    Recombinant human Heme-regulated inhibitor protein
    See all Heme-regulated inhibitor proteins and peptides
  • Biological activity

    The specific activity of ab131665 was determined to be 12 nmol/min/mg.
  • Purity

    > 70 % SDS-PAGE.
    Assessed by densitometry.
  • Expression system

    Baculovirus infected Sf9 cells
  • Accession

  • Protein length

    Full length protein
  • Animal free

  • Nature

    • Species

    • Predicted molecular weight

      120 kDa including tags
    • Amino acids

      1 to 630


Our Abpromise guarantee covers the use of ab131665 in the following tested applications.

The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.

  • Applications

    Western blot

    Functional Studies


  • Form

  • Additional notes

    ab204878 (RS Repeat Peptide peptide) can be utilized as a substrate for assessing kinase activity

    Previously labelled as EIF2AK1. 

  • Concentration information loading...

Preparation and Storage

  • Stability and Storage

    Shipped on dry ice. Upon delivery aliquot and store at -80ºC. Avoid freeze / thaw cycles.

    pH: 7.50
    Constituents: 0.31% Glutathione, 0.002% PMSF, 0.005% DTT, 0.79% Tris HCl, 0.003% EDTA, 25% Glycerol, 0.88% Sodium chloride

    This product is an active protein and may elicit a biological response in vivo, handle with caution.

General Info

  • Alternative names

    • E2AK1_HUMAN
    • EC
    • Eif2ak1
    • Eukaryotic translation initiation factor 2 alpha kinase 1
    • Eukaryotic translation initiation factor 2-alpha kinase 1
    • HCR
    • Heme controlled repressor
    • Heme regulated eukaryotic initiation factor eIF 2 alpha kinase
    • Heme regulated inhibitor
    • Heme regulated initiation factor 2 alpha kinase
    • Heme regulated repressor
    • Heme sensitive initiation factor 2a kinase
    • Heme-controlled repressor
    • Heme-regulated eukaryotic initiation factor eIF-2-alpha kinase
    • Heme-regulated inhibitor
    • Hemin sensitive initiation factor 2 alpha kinase
    • Hemin-sensitive initiation factor 2-alpha kinase
    • HRI
    • KIAA1369
    • PRO1362
    see all
  • Function

    Inhibits protein synthesis at the translation initiation level, in response to various stress conditions, including oxidative stress, heme deficiency, osmotic shock and heat shock. Exerts its function through the phosphorylation of EIF2S1 at 'Ser-48' and 'Ser-51', thus preventing its recycling. Binds hemin forming a 1:1 complex through a cysteine thiolate and histidine nitrogenous coordination. This binding occurs with moderate affinity, allowing it to sense the heme concentration within the cell. Thanks to this unique heme-sensing capacity, plays a crucial role to shut off protein synthesis during acute heme-deficient conditions. In red blood cells (RBCs), controls hemoglobin synthesis ensuring a coordinated regulation of the synthesis of its heme and globin moieties. Thus plays an essential protective role for RBC survival in anemias of iron deficiency. Similarly, in hepatocytes, involved in heme-mediated translational control of CYP2B and CYP3A and possibly other hepatic P450 cytochromes. May also contain ER stress during acute heme-deficient conditions.
  • Tissue specificity

    Expressed predominantly in erythroid cells. At much lower levels, expressed in hepatocytes (at protein level).
  • Sequence similarities

    Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. GCN2 subfamily.
    Contains 2 HRM (heme regulatory motif) repeats.
    Contains 1 protein kinase domain.
  • Post-translational

    Activated by autophosphorylation; phosphorylated predominantly on serine and threonine residues, but also on tyrosine residues. Autophosphorylation at Thr-488 is required for kinase activation. The active autophosphorylated form apparently is largely refractory to cellular heme fluctuations.
  • Cellular localization

  • Information by UniProt


  • The specific activity of Heme-regulated inhibitor (ab131665) was determined to be 14 nmol/min/mg as per activity assay protocol
  • SDS PAGE analysis of ab131665
  • SDS PAGE analysis of ab131665
  • The specific activity of ab131665 was determined to be 12 nmol/min/mg.
  • SDS Page analysis of ab131665


ab131665 has not yet been referenced specifically in any publications.

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