Phosphorylation state of mitochondria and cytosol of 3T3 mouse cells

Preconfluent quiescent 3T3 mouse cells, stimulated into growth with 10% serum, showed little change in their content of ATP per unit protein, or in phosphorylation state (ATP/ADP ratio) which remained near 3.0 during the initial 24 hours. In quiescent, completely confluent cells, the ATP/ADP ratio was reduced to 1.3, but increased to the normal value after 20 hours stimulation with 10% serum. These changes occurred in the cell cytoplasm; in the mitochondria the ATP/ADP ratio remained near 0.5 in both inhibited and growing cells.