De novo protein synthesis and protein phosphorylation during anoxia and recovery in the red-eared turtle

Abstract

Changes in de novo protein synthesis and protein phosphorylation were monitored during anoxia and recovery in the red-eared slider Trachemys (= Pseudemys) scripta elegans. Time courses of 35S-radiolabeled methionine incorporation into acid-precipitable material showed an increase up to 5 h postinjection and remained constant after this time. Comparison of the total and acid-precipitable 35S label incorporation into tissues from 20-h control, anoxic, and recovering animals showed differences between these groups: total radioactivity in brain was 2.9-fold lower in recovering turtles, whereas protein-associated radioactivity was 2.4-fold higher in anoxic liver, 2.3-fold lower in recovering skeletal muscle, and 3.7-fold lower in recovering brain tissue. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radiolabeled proteins showed the existence of a newly synthesized protein band (relative molecular mass = 72 kDa) that was apparent only in 20-h recovering liver and skeletal muscle. Use of 32P labeling to monitor changes in protein phosphorylation patterns during anoxia revealed 1.6-, 1.4-, and 1.5-fold increases in 32P incorporation in anoxic brain, heart, and liver, respectively. Changes in protein phosphorylation were localized to the plasma membrane and cytosolic fractions in brain and to the cytosolic fraction in liver.