[Threonyl-tRNA synthase from rabbit reticulocytes: a reversible transition from the RNA-non-binding to the...

A simple three-step procedure was used to isolate threonyl-tRNA synthetase of rabbit reticulocytes which is in a ribosome-free extract in the RNA-non-binding form. According to SDS electrophoresis, the enzyme has a molecular weight of 86 000 Da and is heterogeneous by isoelectric point; pI of the major component is near 6.2. Threonyl-tRNA synthetase is capable of interacting with a high molecular weight RNA (E. coli rRNA). Thus, in the course of purification threonyl-tRNA synthetase passes from the RNA-non-binding to the RNA-binding form. This transition was shown to be reversible.