Heterogeneity of native rat liver elongation factor 2.
The high heterogeneity of native rat liver EF-2 prepared from either 105000 x g supernatant or microsome high-salt extract was detected by two-dimensional equilibrium isoelectric focusing-SDS-polyacrylamide gel electrophoresis in the presence of 9.5 M urea. Five spots were always detected, all of Mr 95,000, which were not artefactual for their amount varied when EF-2 was specifically ADP-ribosylated by diphtheria toxin in the presence of NAD+, and/or phosphorylated on a threonine residue by a Ca2+/calmodulin-dependent protein kinase (most likely Ca2+/calmodulin-dependent protein kinase III described by others [(1987) J. Biol. Chem. 262, 17299-17303; (1988) Nature 334, 170-173]). Results of ADP-ribosylation and/or phosphorylation experiments with either unlabeled or labeled reagents ([14C]NAD and [32P]ATP) strongly suggest that our preparation contained native ADP-ribosylated and native phosphorylated forms which could be estimated at about 20% and 40% of the whole EF-2. Phosphorylated and ADP-ribosylated forms of EF-2 could be ADP-ribosylated and phosphorylated, respectively, but a native form both ADP-ribosylated and phosphorylated was not detected. Our results also suggest the existence of a minor native form of EF-2 and of its phosphorylated and ADP-ribosylated derivatives.
Marzouki
A
A
Laboratoire de Biochimie Médicale, Université Lyon I, UM CNRS 24, Villeurbanne, France.
Lavergne
J P
JP
Reboud
J P
JP
Reboud
A M
AM
D000246:Adenosine Diphosphate Ribose / Q000302:isolation & purification; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D008862:Microsomes, Liver / Q000032:analysis*; D015394:Molecular Structure; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000302:isolation & purification*; D010766:Phosphorylation; D051381:Rats
D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D000246:Adenosine Diphosphate Ribose