Phosphorylation of eukaryotic aminoacyl-tRNA synthetases

Thesis/Dissertation · Tue Dec 31 23:00:00 EST 1985

OSTI ID:6721909

Pendergast, A M

The phosphorylation of the highly purified aminoacyl-tRNA synthetase complex from rabbit reticulocytes was examined. The synthetase complex contained, in addition to eight aminoacyl-tRNA synthetases, three unidentified proteins and was free of endogenous protein kinase activity. Incubation of the complex with casein kinase I in the presence of ATP resulted in the phosphorylation of four synthetases, the glutamyl-, isoleucyl-, methionyl-, and lysyl-tRNA synthetases. Phosphorylation by casein kinase I altered binding to tRNA-Sepharose such that the phosphorylated complex eluted at 190 mM NaCl instead of the 275 mM salt observed for the nonphosphorylated form. Phosphorylation by casein kinase I resulted in a significant inhibition of aminoacylation with the four synthetases; the activities of the nonphosphorylated synthetases were unchanged. One of the unidentified proteins in the complex (M/sub r/ 37,000) was also an excellent substrate for casein kinase I. A comparison of the properties and two-dimensional phosphopeptide pattern of this protein with that of casein kinase I suggest that the 37,000 dalton protein in the synthetase complex is an inactive form of casein kinase I. Two other protein kinases were shown to phosphorylate aminoacyl-tRNA synthetases in the complex. The phosphorylation of threonyl-tRNA synthetase was also investigated. Five aminoacyl-tRNA synthetases in the high molecular weight complex were shown to be phosphorylated in rabbit reticulocytes following labeling with (/sup 32/P)orthophosphate.

• Research Organization: California Univ., Riverside (USA)
• OSTI ID: 6721909
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACYLATION
ANIMALS
ATP
BIOCHEMISTRY
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHEMICAL REACTIONS
CHEMISTRY
ENZYMES
ERYTHROCYTES
LIGASES
MAMMALS
MATERIALS
NUCLEIC ACIDS
NUCLEOTIDES
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
RABBITS
RETICULOCYTES
RNA
TRANSFER RNA
TRANSFERASES
VERTEBRATES