Regulation of protein synthesis by heme-regulated eIF-2 alpha kinase.
Protein synthesis is regulated by the phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF-2 alpha) in a variety of cells. At present, there are two distinct mammalian eIF-2 alpha kinases that have been cloned, the double-stranded-RNA-dependent eIF-2 alpha kinase (PKR) and the heme-regulated eIF-2 alpha kinase (HRI). HRI is activated under conditions of heme deficiency in immature erythroid cells, and its activity is inhibited by heme. The high levels of HRI in reticulocytes indicate that its major physiological role is the regulation of protein synthesis, particularly of hemoglobin, according to the concentration of heme in these cells.
Chen
J J
JJ
Massachusetts Institute of Technology, Harvard-MIT Division of Health Sciences and Technology, Cambridge 02139, USA.
London
I M
IM
D000818:Animals; D006360:Heat-Shock Proteins / Q000378:metabolism; D006418:Heme / Q000378:metabolism*; D006801:Humans; D014176:Protein Biosynthesis; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D019892:eIF-2 Kinase
D006360:Heat-Shock Proteins; D006418:Heme; D017346:Protein Serine-Threonine Kinases; D019892:eIF-2 Kinase