TRANSFER-RNA(TRP) AS COFACTOR OF GELONIN, A RIBOSOME-INACTIVATING PROTEIN WITH RNA-N-GLYCOSIDASE ACTIVITY - FEATURES REQUIRED FOR THE COFACTOR ACTIVITY

Purified beef and rabbit liver tRNA(Trp), but not yeast tRNA(Trp), inc rease the in vitro inactivation of eukaryotic ribosomes by gelonin, a ribosome-inactivating protein with RNA-N-glycosidase activity on 2BS r RNA. Aminoacylation and stepwise trimming of the 3'-end of bovine tRNA (Trp) affect the cofactor activity, the most active species being that shortened by the last two nucleotides. ATP only moderately increases the activity of purified mammalian tRNA(Trp) and in this increase the cognate aminoacyl-tRNA synthetase apparently has no role. Mobility shi ft experiments indicate that bovine tRNA(Trp) binds both to ribosomes and to gelonin and favours the dissociation of gelonin from ribosomes.