title: The NH2-terminal sequence of the alpha and gamma subunits of eukaryotic initiation factor 2 and the phosphorylation site for the heme-regulated eIF-2 alpha kinase.
abstract: Rabbit reticulocyte eukaryotic initiation factor 2 was phosphorylated with the heme-regulated alpha subunit of eukaryotic initiation factor 2 kinase, and then the individual subunits were resolved by reversed-phase high performance liquid chromatography. Phosphorylated and unphosphorylated forms of the alpha subunit also were well resolved. The NH2-terminal sequences of intact alpha and gamma subunits were determined. No sequence was obtained from the beta subunit, suggesting that it may have a blocked NH2-terminus. Overlapping tryptic and chymotryptic phosphopeptides from the NH2-terminal sequence of the alpha subunit of eukaryotic initiation factor 2 were used to establish the order of amino acids 1-52 and localized the phosphorylation site within the sequence: -Leu-Leu-Ser48-Glu-Leu-Ser51-. Subdigestion of a tryptic fragment with chymotrypsin generated only phosphopeptides that appeared to terminate at leucine 50, indicating phosphorylation at serine 48.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2; D006418:Heme / Q000494:pharmacology*; D010446:Peptide Fragments / Q000032:analysis; D010448:Peptide Initiation Factors / Q000032:analysis*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000032:analysis*; D011817:Rabbits; D014357:Trypsin / Q000378:metabolism
chemical_list: D015852:Eukaryotic Initiation Factor-2; D010446:Peptide Fragments; D010448:Peptide Initiation Factors; D011506:Proteins; D006418:Heme; D011494:Protein Kinases; D002918:Chymotrypsin; D014357:Trypsin