RNA radiolabeling.

Radioactive end-labeling is useful for visualizing and allowing the detection of nucleic acids at trace concentrations. Radioactive end-labeling can be carried out on RNA, DNA, or other modified nucleic acids. For RNA, the uses of end-labeling extend beyond simple detection of the intact RNA. A number of RNA molecules studied by biologists form three-dimensional structures in solution, and many of the techniques used to study these structures depend on the ability to visualize the RNA after fragmentation. Labeling at either the 5'- or 3'-end serves as a gateway into these structural analysis techniques (see Structural Analysis of RNA Backbone Using In-Line Probing), and protocols for these labeling procedures are described below (for a nonradiactive labeling protocol, see Fluorescently Labeling Synthetic RNAs).