HNRNP-CELLS FROM HELA-CELLS CONTAIN A RIBONUCLEASE ACTIVE ON DOUBLE-STRANDED-RNA

A ribonuclease D, i-e acting against double-stranded RNA structures like poly r(AU), was identified in ribonucleoprotein structures containing the heterogenous nuclear RNA (hnRNP) from HeLa cells. This activity could not however be detected in intact hnRNP but only after passage through a DEAE-cellulose column or digestion by a combination of ribonucleases A+T1. This enzyme does not degrade poly r(A)-poly d(T) nor poly r(A), nor does it yield mononucleotides, excluding the possibility of a non-specific exonuclease type of activity like phosphodiesterase. It is inhibited by ethidium bromide and double-stranded RNA and resembles in all respects so far investigated the ribonuclease D previously isolated from Krebs cells by Rech et al (Nucl. Acids Res. 1976, 3, 2055-2065). © 1979.