A Comparative Study of Different Types of Rabbit 2',5'-Oligoadenylate Synthetase

Only one 2',5'-oligoadenylate synthetase (2',5'-OASE) with a mass of 110 kD is present in the NDV-induced rabbit reticulocytes, whereas two 2',5'-OASE isozymes with mass of 110 kD and 40 kD respectively exist in the NDV-treated rabbit spleen. The large 110 kD enzymes from reticulocytes and spleen are associated with the ribosome. The small enzyme from spleen has been found in both the cytosol and ribosomal pellet. The characterization of the large enzymes purified from NDV-induced reticulocytes and spleen show that the 110 kD enzymes are the same one, and identical to the enzyme from phenylhydrazine-induced rabbit reticulocytes, suggesting that they are most likely encoded by the same gene, although their induction pathway and tissue distribution pattern are different. It is postulated that the 40 kD 2',5'-OASE from rabbit spleen and the large enzyme are isozymes with different physiological functions, considering that they require different conditions for catalytic reaction reaction and are located in different subcellular fractions.