Transfer RNA binding protein in the nucleus of Saccharomyces cerevisiae

A yeast nuclear protein that binds to tRNA was identified using a RNA mobility shift assay. Northwestern blotting and N-terminal sequencing experiments indicate that this tRNA-binding protein is identical to zuotin which has previously been shown to bind to Z-DNA [(1992) EMBO J. 11, 3787-3796]. Labeled tRNA and poly(dG-m5dC) stabilized in the Z-DNA form identify the same protein on a Northwestern blot. In a gel retardation assay poly(dG-m5dC) in the Z-form strongly diminishes the binding of tRNA to zuotin. These studies establish that zuotin is able to bind to both tRNA and Z-DNA. Zuotin may be transiently associated with tRNA in the nucleus of yeast cells and play a role in its processing or transport to the cytoplasm.