Purification of a human polyribosome-associated 3' to 5' exoribonuclease.

摘要: Abstract In cells and cell-free extracts, the early steps in histone mRNA decay occur at 3' terminus appear to be catalyzed by a polysome-associated 5' exoribonuclease. We describe purification of polysomal exoribonuclease that is magnesium-dependent, active pH 7-8 salt concentrations below 200 mM, resistant inhibitor RNase A family RNases. The purified enzyme inactive with 3'-phosphorylated RNA substrates DNA but can degrade duplex absence added ATP. migrates approximately 37 kDa native state gel filtration 33 SDS-polyacrylamide gel. It degrades poly(A) not complex binding protein, it accelerates high salt-washed (enzyme-depleted) polysomes. Similarities between activity vitro suggest might mammalian messenger ribonuclease.