A 2ND NITROGEN PERMEASE REGULATOR IN SACCHAROMYCES-CEREVISIAE

We describe a Saccharomyces cerevisiae mutant affected in its urea and proline transport capacities, and a gene coding for a protein complem enting this mutation, This protein is not membrane-embedded and contai ns two PEST sequences, often found in regulatory factors, The mRNA is not down-regulated under nitrogen catabolite repression, and is induce d by urea and proline, In the mutant, the PUT4 mRNA encoding the proli ne permease is not affected, whereas the DUR3 mRNA, involved in urea a ctive transport, is strongly increased, Our data suggest that this pro tein is a post-transcriptional regulator of nitrogen permeases.