In vitro transcripts of a yeast variant 5 S rRNA gene exhibit alterations in 3'-end processing and protein binding.

When a yeast 5 S rRNA gene with a variant 3'-terminal nucleotide sequence was transcribed in a homologous cell-free system, primary transcripts that were shorter, more heterogeneous in length and much more resistant to processing than pre-5 S rRNA from the major "repeat" 5 S rRNA gene were produced. After 3'-end processing, variant 5 S rRNA was one nucleotide shorter than mature repeat 5 S rRNA and was bound much less strongly to ribosomal protein YL3. The stable variant pre-5 S rRNA appeared to bind another, unidentified protein. The formation of this presumptive ribonucleoprotein complex was disrupted by (Up)4UOH, suggesting that it may contain a yeast analog of the mammalian La protein.