These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Site-specific phosphorylation if initiation factor 2 by three cyclic nucleotide-independent protein kinases.
    Author: Tuazon PT, Merrick WC, Traugh JA.
    Journal: J Biol Chem; 1980 Nov 25; 255(22):10954-8. PubMed ID: 7430164.
    Abstract:
    The site-specific phosphorylation of initiation factor 2 (eIF-2) by three different cyclic nucleotide-independent protein kinases from rabbit reticulocytes was examined. The hemin-controlled repressor modified serine in the alpha subunit (Mr = 38,000), while casein kinase II and protease-activated kinase II phosphorylated serine residues of the beta subunit (Mr = 53,000). Under conditions of maximal phosphorylation, 1 mol of phosphate was incorporated into eIF-2 by each of the protein kinases. However, following treatment of eIF-2 with alkaline phosphatase, 2 mol of phosphate were added by casein kinase II, indicating residual phosphate was present on the beta subunit of purified eIF-2. The tryptic and chymotryptic peptides of the phosphorylated subunits were analyzed by two-dimensional peptide mapping involving thin layer electrophoresis followed by ascending chromatography. When eIF-2 was phosphorylated by the hemin-controlled repressor, three major chymotryptic and four tryptic phosphopeptides with molecular weights ranging from approximately 600 to 3000 were identified. When phosphorylation of eIF-2 beta was examined, two tryptic and two chymotryptic phosphopeptides were obtained after phosphorylation with casein kinase II and were different from the phosphopeptides observed following phosphorylation with protease-activated kinase II. This indicates that three distinct sites in the beta subunit were phosphorylated, two by casein kinase II and one by protease-activated kinase II.
    [Abstract] [Full Text] [Related] [New Search]