Nonradioactive 3′-End-Labeling of RNA Molecules of Different Lengths by Terminal Deoxynucleotidyltransferase

Terminal deoxynucleotidyltransferase is well known for its ability to add nucleotides to the 3'-ends of DNA; here we demonstrate a corresponding activity with RNA as acceptor molecule. Using DIG- or biotin-dUTP as substrate, a tailing reaction is used for nonradioactive 3'-end-labeling of RNA oligonucleotides, isolated RNA molecules such as tRNA from E. coli, and MS2 RNA as well as in vitro transcripts. The tail length and associated sensitivity of detection can be varied using DIG-ddUTP, DIG-dUTP, or a nucleotide mixture of DIG-dUTP and dATP.