CYCLIC 2',3'-PHOSPHATES AND NONTEMPLATED NUCLEOTIDES AT THE 3' END OF SPLICEOSOMAL U6 SMALL NUCLEAR RNAS

Spliceosomal U6 small nuclear RNA (U6 RNA) in species as diverse as man, frog, fruitfly, and soybean have at their 3' ends a cyclic 2',3'-phosphate (> p) apparently derived from uridylic acid residues that were added post-transcriptionally. The 3' ends of U6 RNA's from various sources may be processed in different ways, or to different extents, depending on the organism or stage of development. The presence of a > p terminus on U6 RNA may influence the activity of U6 RNA either directly during splicing or indirectly by ensuring that the RNA has a defined length or proper conformation (or both).