Eukaryotic tryptophanyl-tRNA synthetase acquires affinity to high molecular weight RNA after limited proteolysis

It is shown that the native tryptophanyl-tRNA synthetase (Mr 2X60 kDa) isolated from bovine pancreas does not interact with high-molecular weight RNAs (E. coli rRNAs). The enzyme acquires the affinity for high-molecular weight RNAs after the cleavage of the 20 kDa fragment from each of the subunits upon digestion by protease. The possible functional significance of the discovered phenomenon is discussed.