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. Author manuscript; available in PMC: 2007 Jul 20.
Published in final edited form as: Mol Cell. 2007 Apr 27;26(2):217–229. doi: 10.1016/j.molcel.2007.04.007

Figure 1. Structure of 35S Pre-rRNA and the rRNA Processing Intermediates in the Major rRNA Processing Pathways in S. cerevisiae.

Figure 1

(A) Positions of two internal transcribed spacers (ITS1 and ITS2) and 5′ and 3′ external transcribed spacers (ETS) are shown. Pre-rRNA cleavage sites are indicated by upper-case letters. Lower-case letters indicate the location of oligonucleotide probes used for northern hybridization and primer extension.

(B) The major pre-rRNA processing pathways adapted from Venema and Tollervey (1999). The 27SA2 pre-rRNA is processed by two alternative pathways, giving rise to two forms of 5.8S rRNA, the major short form 5.8Ss, and a minor long form 5.8SL. Exonuclease activities are indicated by circles with cutouts.