Purification and properties of the double-stranded RNA-activated eukaryotic initiation factor 3 kinase from rabbit reticulocytes.
The double-stranded RNA (dsRNA)-activated protein kinase (DAI) that phosphorylates the alpha subunit of the eukaryotic initiation factor eIF-2 and inhibits chain initiation has been isolated from rabbit reticulocyte lysates. The nonactivated enzyme or the enzyme partially activated by incubation with low levels of dsRNA (pro-DAI) could be purified only to a slight extent. However, the enzyme that was fully activated by incubation with both dsRNA and ATP was purified to near homogeneity. Active DAI is a phosphoprotein with an apparent subunit mass of 68,000 daltons. It can phosphorylate histone as well as the alpha subunit of eIF-2. Our results suggest that, after interaction with dsRNA, the enzyme phosphorylates itself and is thereby activated to phosphorylate alpha eIF-2 and histone.
D000818:Animals; D004789:Enzyme Activation; D006657:Histones / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000201:enzymology*
D006657:Histones; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D012330:RNA, Double-Stranded; D011494:Protein Kinases