PROTEIN SYNTHESIS IN ERYTHROID CELLS, I. RETICULOCYTE RIBOSOMES ACTIVE IN STIMULATING AMINO ACID INCORPORATION

Abstract

glucose-l-C'4 oxidation would allow for either stimulation in the forward or reverse manner.The direction of the stimulation is then most probably a function of the ratio of the concentrations of oxidized and reduced diphosphopyridine and triphos- phopyridine nucleotides.If in the anterior pituitary ATP synthesis via oxidative phosphorylation can be considered a consequence of DPNH formation, this transhydrogenase activity could provide a sensitive mechanism for its control.ATP thus formed upon stim- ulation of the transhydrogenase by serotonin or epinephrine could be used in either peptide synthesis or peptide secretion as proposed by Hokin for ACTH.I2Summary.-Glucose oxidation in the anterior pituitary is dependent on the concentration of available TPN.There is in anterior pituitary enzymic activity, prob- ably located in mitochondria, which catalyzes the transfer of hydrogen from TPNH or DPNH to 3-acetylpyridine*DPN.This transhydrogenase activity can be stimulated by several compounds of biological importance including serotonin, epinephrine, and estradiol and can be linked to glucose-6-phosphate dehydrogenase.It is suggested that ultimately ATP synthesis may be regulated by this hormonally sensitive pyridine nucleotide transhydrogenase.