To determine whether there are differences between the U1, U2, and
U3 small nuclear RNA's of human
cancer cells (HeLa cells) and human normal fibroblasts (IMR-90 cells), and between these
uridine-rich
small nuclear RNA's of human and
Novikoff hepatoma cells, the cells were first incubated in Eagle's medium with [32P]Pi to label these
RNA's uniformly. No differences were found between the
RNase T1 fingerprints of the purified U1, U2, and U3
RNA's of HeLa cells and IMR-90 cells. The
RNase T1 fingerprints of
U1 RNA's from human tissues were very similar to that of the
U1 RNA of
Novikoff hepatoma cells. The
RNase T1 fingerprints of U2 and U3
RNA's from human tissues had many similarities to those of
Novikoff hepatoma cells, but a few differences were found, such as a point mutation of the U-U-Gp in the rat
U2 RNA to A-U-Gp (U leads to A) in human
U2 RNA. Unlike the three U3
RNA's of
Novikoff hepatoma cells, U3
RNA from human tissues appears to be only one species. These results indicate that U1, U2, and U3
RNA's of human
cancer cells are essentially the same as those of human normal cells. In addition, the
uridine-rich
small nuclear RNA's appear to be conserved through evolution.