The synthesis of hemoglobin and non-hemoglobin protein of amphibian red blood cells related to metamorphosis

Abstract

1. 1. Protein synthesis (incorporation of [ 14C]phenylalanine) was studied in tadpole ( Rana catesbiana) red blood cell suspensions. Since hemoglobin changes during metamorphosis, red blood cells were examined from animals in different stages of development, in the winter and summer, and after injection of l-thyroxine. The non-hemoglobin protein of tadpole red blood cells was found to be involved in metamorphosis; it was isolated and characterized. 2. 2. Protein synthesis in tadpole red cells was inhibited by puromycin and chloramphenicol. The incorporation of [2- 14C]uridine into nucleic acid was observed and was reduced by actinomycin D. 3. 3. Hemoglobin was the main protein synthesized by red cells of winter tadpoles (stages XI–XIII). Protein synthesis was reduced in red cells of summer tadpoles of all stages; non-hemoglobin protein was synthesized preferentially. After thyroxine injection red cells from winter animals behaved similarly to red cells from summer animals of the same stage. The non-hemoglobin protein amounts to 5–10% of hemoglobin and disappears late in metamorphosis when the adult hemoglobin appears. 4. 4. Non-hemoglobin protein has an s 0.5% 20 2.3, a molecular weight of 30 000 and is heterogeneous on electrophoresis. The protein has no carbonic anhydrase activity and no cysteine (similar to tadpole hemoglobin). 5. 5. The possible identity of the non-hemoglobin protein with globin subunits or apoferritin subunits is considered.