Mechanism of elongation factor 2 (EF-2) inactivation upon phosphorylation. Phosphorylated EF-2 is unable to catalyze translocation.
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.
Ryazanov
A G
AG
Institute of Protein Research, Academy of Sciences of the USSR, Pushchino, Moscow Region.
Davydova
E K
EK
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010766:Phosphorylation; D011072:Poly U / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011691:Puromycin / Q000378:metabolism; D012360:RNA, Transfer, Phe / Q000378:metabolism; D011817:Rabbits; D012270:Ribosomes / Q000378:metabolism; D013329:Structure-Activity Relationship
D002147:Calmodulin; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D012360:RNA, Transfer, Phe; D011072:Poly U; C011265:guanosine 5'-(beta,gamma-methylene)triphosphate; D006165:Guanylyl Imidodiphosphate; D011691:Puromycin; D006160:Guanosine Triphosphate; D011494:Protein Kinases; D002118:Calcium