Eukaryotic Translation Initiation Factor 2-Alpha Kinase HRI (HRI)

HRI is a key regulator of protein synthesis in mammalian cells, acting as a kinase that phosphorylates the alpha subunit of eukaryotic translation initiation factor 2 (eIF2α) in response to various cellular stresses. Its primary function is to sense heme availability and other stress signals, such as oxidative stress, osmotic shock, mitochondrial dysfunction, and heat shock. Upon activation, HRI phosphorylates eIF2α, which inhibits the recycling of eIF2 and leads to a global reduction in protein synthesis while allowing selective translation of specific mRNAs involved in the integrated stress response (ISR). This mechanism helps cells adapt by reprogramming gene expression during periods of metabolic or environmental stress. It is predominantly expressed in erythroid precursors and plays an essential role during erythropoiesis by coordinating ribosomal protein translation. Dysregulation can lead to ineffective erythropoiesis due to unrestrained globin synthesis when heme is limiting. It may also play roles in neurodegeneration or immune dysfunction.

Other names

Heme-Regulated InhibitorEIF2AK1E2AK1_HUMAN

Inhibition of eIF2α recycling via phosphorylation, leading to global reduction in cap-dependent protein synthesis and selective translation of stress-related mRNAs.