Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cell-free extract from wheat germ contains an inhibitor interfering with translation of a natural template (BMV RNA). The inhibitor affects neither the translation of poly(U) nor the aminoacylation of tRNA. It exhibits the activity of protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37). The inhibitor is found in lipoprotein aggregates which can be separated from ribosomes on Sepharose 2B column. Ribosomes purified on the Sepharose are several times more active in translation of BMV RNA than those isolated by conventional methods.
 ...
PMID:Isolation of wheat ribosomes free of high molecular weight inhibitors of the natural messenger translation. 50 12

Previously we have found that elongation factor 2 (EF-2) from mammalian cells can be phosphorylated by a special Ca2+/calmodulin-dependent protein kinase (EF-2 kinase). Phosphorylation results in complete inactivation of EF-2 in the poly(U)-directed cell-free translation system. However, the partial function of EF-2 affected by phosphorylation remained unknown. Here we show that phosphorylated EF-2, unlike non-phosphorylated EF-2, is unable to switch ribosomes carrying poly(U) and Phe-tRNA in the A site to a puromycin-reactive state. Thus, phosphorylation of EF-2 seems to block its ability to promote a shift of the aminoacyl(peptidyl)-tRNA from the A site to the P site, i.e. translocation itself.
 ...
PMID:Mechanism of elongation factor 2 (EF-2) inactivation upon phosphorylation. Phosphorylated EF-2 is unable to catalyze translocation. 275 58

The major substrate for Ca2+/calmodulin-dependent protein kinase III in mammalian cells is a species of Mr 100,000 that has a primarily cytoplasmic localization. This substrate has now been identified as elongation factor-2 (EF-2), a protein that catalyzes the translocation of peptidyl-tRNA on the ribosome. The amino acid sequence of 18 residues from the N-terminal of the Mr 100,000 CaM-dependent protein kinase III substrate purified from rat pancreas was found to be identical to the N-terminal sequence of authentic rat EF-2 as previously deduced from nucleic acid sequencing of a cDNA (Kohno, K., Uchida, T., Ohkubo, H., Nakanishi, S., Nakanishi, T., Fukui, T., Ohtsuka, E., Ikehara, M., and Okada, Y. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 4978-4982). CaM-dependent protein kinase III phosphorylated EF-2 in vitro with a stoichiometry of approximately 1 mol/mol on a threonine residue. Amino acid sequencing of the purified tryptic phosphopeptide revealed that this threonine residue lies within the sequence: Ala-Gly-Glu-Thr-Arg-Phe-Thr-Asp-Thr-Arg (residues 51-60 of EF-2). The Mr 100,000 protein was stoichiometrically ADP-ribosylated in vitro by the addition of diphtheria toxin and NAD. The Mr 100,000 protein was photoaffinity labeled with a GTP analog and the protein had an endogenous GTPase activity that could be stimulated by the addition of salt-washed ribosomes. These properties are all characteristic of EF-2. Dephospho-EF-2 could support poly(U)-directed polyphenylalanine synthesis in a reconstituted elongation system when combined with EF-1. In the same system, phospho-EF-2 was virtually inactive in supporting polypeptide synthesis; this effect could be reversed by dephosphorylation of phospho-EF-2. These results suggest that intracellular Ca2+ inhibits protein synthesis in mammalian cells via CaM-dependent protein kinase III-catalyzed phosphorylation of EF-2.
 ...
PMID:Identification of the major Mr 100,000 substrate for calmodulin-dependent protein kinase III in mammalian cells as elongation factor-2. 369 53

A chimeric Ca2+/calmodulin-dependent protein kinase (CCaMK) was previously cloned and characterized in this laboratory. To investigate the biological functions of CCaMK, the yeast two-hybrid system was used to isolate genes encoding proteins that interact with CCaMK. One of the cDNA clones obtained from the screening (LlEF-1alpha1) has high similarity with the eukaryotic elongation factor-1alpha (EF-1alpha). CCaMK phosphorylated LlEF-1alpha1 in a Ca2+/calmodulin-dependent manner. The phosphorylation site for CCaMK (Thr-257) was identified by site-directed mutagenesis. Interestingly, Thr-257 is located in the putative tRNA-binding region of LlEF-1alpha1. An isoform of Ca2+-dependent protein kinase (CDPK) phosphorylated multiple sites of LlEF-1alpha1 in a Ca2+-dependent but calmodulin-independent manner. Unlike CDPK, CCaMK phosphorylated only one site, and this site is different from CDPK phosphorylation sites. This suggests that the phosphorylation of EF-1alpha by these two kinases may have different functional significance. Although the phosphorylation of LlEF-1alpha1 by CCaMK is Ca2+/calmodulin-dependent, in vitro binding assays revealed that CCaMK binds to LlEF-1alpha1 in a Ca2+-independent manner. This was further substantiated by coimmunoprecipitation of CCaMK and EF-1alpha using the protein extract from lily anthers. Dissociation of CCaMK from EF-1alpha by Ca2+ and phosphorylation of EF-1alpha by CCaMK in a Ca2+/calmodulin-dependent manner suggests that these interactions may play a role in regulating the biological functions of EF-1alpha.
 ...
PMID:Interaction of plant chimeric calcium/calmodulin-dependent protein kinase with a homolog of eukaryotic elongation factor-1alpha. 1020 22