Two conserved domains of yeast U2 snRNA are separated by 945 nonessential nucleotides

摘要: Yeast U2 snRNA (1175 nucleotides) is six times larger than its mammalian counterpart (188 nucleotides). Using deletion analysis, we show that the molecule can be divided into three phenotypically distinct domains. As expected, highly conserved 5' domain (approximately 120 absolutely essential for viability. Surprisingly, however, of central 945 nucleotides has no effect on growth rate. In contrast, removal sequences in 3' terminal 110 results low numbers slow-growing colonies; these cells contain with altered ends. This folded a secondary structure strongly resembles stem-loop IV human U2. We conclude yeast contains two functionally important elements. While known to directly involved splicing reaction, may function primarily generation stable small nuclear ribonucleoprotein particles.