The 90-kilodalton peptide of the heme-regulated eIF-2 alpha kinase has sequence similarity with the 90-kilodalton heat shock protein.
Highly purified preparations of the heme-controlled eIF-2 alpha (eukaryotic peptide initiation factor 2 alpha subunit) kinase of rabbit reticulocytes contain an abundant 90-kilodalton (kDa) peptide that is immunologically cross-reactive with spectrin and that modulates the activity of the enzyme [Kudlicki, W., Fullilove, S., Read, R., Kramer, G., & Hardesty, B. (1987) J. Biol. Chem. 262, 9695-9701]. The amino-terminal sequence of the 90-kDa protein has a high degree of similarity with the known amino-terminal sequences of the Drosophila 83-kDa heat shock protein (20 out of 22 residues) and with other related heat shock proteins. The amino acid sequence of a tryptic phosphopeptide isolated by high-performance liquid chromatography from the eIF-2 alpha kinase associated 90-kDa protein after phosphorylation by casein kinase II is shown to be identical with a 14 amino acid segment of the known sequence of the Drosophila 83-kDa heat shock protein. Results of hydrodynamic studies indicate a highly elongated structure for the reticulocyte protein, characteristic of a structural protein. Additional structural similarities between the eukaryotic heat shock proteins, the reticulocyte eIF-2 alpha kinase associated 90-kDa peptide, and spectrin are discussed.
Clayton Foundation Biochemical Institute, Austin, Texas.
D W
DW
Rose
R E
RE
Wettenhall
W
W
Kudlicki
G
G
Kramer
B
B
Hardesty
D000595:Amino Acid Sequence; D000818:Animals; D006360:Heat-Shock Proteins / Q000235:genetics*; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics* / Q000302:isolation & purification; D011817:Rabbits; D012156:Reticulocytes / Q000201:enzymology; D014357:Trypsin; D019892:eIF-2 Kinase
D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D010446:Peptide Fragments; D010748:Phosphopeptides; D011494:Protein Kinases; D019892:eIF-2 Kinase; D014357:Trypsin