DE-NOVO PROTEIN-SYNTHESIS AND PROTEIN-PHOSPHORYLATION DURING ANOXIA AND RECOVERY IN THE RED-EARED TURTLE

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 S-35-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 S-35 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 P-32 labeling to monitor changes in protein phosphorylation patterns during anoxia revealed 1.6-, 1.4-, and 1.5-fold increases in P-32 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.