DISTRIBUTION OF THE NUCLEASES OF THE MICROSOMAL FRACTION OF RAT LIVER BETWEEN RIBOSOMES AND ENDOPLASMIC MEMBRANES

Abstract

The distribution of nucleases of the microsomal fraction of rat liver between ribosomes and endoplasmic membranes was studied. The results show that the ribosomes contained a ribonuclease (RNase) inhibited by Mg++ions but activated by ethylenediaminetetraacetic acid (EDTA). Furthermore the degradation products of this enzyme were found to possess a 3′-phosphomonoester end group. The endoplasmic membranes contained a 5′-RNase that could degrade the purine—purine linkage of polyadenylic acid, and a 5′-phosphodiesterase.