ATP(CTP)-tRNA nucleotidyltransferase catalyzes the incorporation of AMP and CMP residues into tRNA molecules from which all, or part, of the 3 terminal trinucleotide sequence, –C–C–A, has been removed. tRNA nucleotidyltransferase activity has been identified in a wide variety of organisms including mammals, birds, amphibians, insects, and bacteria. In addition, the enzyme has been shown to be present in mammalian mitochondria and to be associated with a variety of RNA tumor viruses and Sendai virus. The significant interest generated in tRNA nucleotidyltransferase is mainly because of its role in processing and repairs of tRNA, its study as a model enzyme for phosphodiester bond synthesis, and its usefulness as a reagent for modifying or labeling the 3′ terminus of tRNA. tRNA nucleotidyltransferase activity is measured by incorporation of radioactive ATP or CTP into an acid-insoluble form. tRNA molecules lacking one, two, or three terminal residues may be used as acceptors depending on whether ATP or CTP is the donor. tRNA nucleotidyltransferase is present in cells in extremely small amounts, therefore purifications of 5000- to 25,000-fold is often required.
ASJC Scopus subject areas
- Molecular Biology