Endonuclease involved in pre-rRNA processing at both ends of ITS2%3B functions with Grc3p in a conserved mechanism to modulate rRNA processing and ribosome biogenesis%3B may coordinate the action of the Rat1p-Rai1p exoRNAse%3B required for the G1/S cell cycle transition%3B human ortholog is Las1L%3B mutants require the SSD1-v allele for viability