Kinetics of synthesis and characterization of transfer RNA precursors in mammalian cells

Evidence that mammalian cell tRNA has at least one precursor stage prior to maturation is presented. This is supported by the finding of species of RNA from Chinese hamster ovary cells and Ehrlich ascites tumor cells that migrate between 5-S ribosomal RNA and 4-S RNA on both acrylamide gel and Sephadex G-200 columns. This species of RNA has been purified from Ehrlich ascites tumor cells and has been shown to contain pseudouridine and dihydrouridine and found to be undermethylated when compared to matured tRNA. Kinetic studies confirm the precursor-product relationship of the molecules. The half-life of the precursor tRNA is about 12–15 min.