Ribonuclease inhibitors from mouse ascites cells.

Ribonuclease inhibitors were found to be present attached to mouse ascites ribosomes and in the post-ribosomal supernatant. Both inhibitors inhibited pancreatic RNAses A and B and two endonucleases prepared from ascites cells but did not inhibit RNAses T1 or N1. Both inhibitors had the same sedimentation coefficient and this taken with the results above suggest that they are identical. The inhibitor was shown to interact directly with the RNAse itself.