The RHO4a and NUD1 genes on Saccharomyces cerevisiae chromosome XI.

Sequence analysis of a 4 kb fragment from the right arm of Saccharomyces cerevisiae chromosome XI, in combination with Northern hybridization experiments revealed the presence of two genes, designated RHO4a and NUD1. The first gene encodes a 32 kDa protein showing significant sequence similarity with members of the ras family. Its 3'-terminal sequence is virtually identical to a sequence published previously as the RHO4 gene [Matsui and Toh-e, Gene 114 (1992), 43-49], which, however, appears to start at an internal ATG codon. The RHO4a sequence also overlaps the 5'-terminal sequence of the RNC1 gene [Chow et al., Nucl. Acids Res. 20 (1992), 5215-5221] proposed to encode the yeast yNucR endo/exonuclease. The remainder of this RNC1 gene overlaps with the 5'-end of the NUD1 gene. However, the RNC1 sequence lacks a portion of 276 bp that in our fragment is part of the intergenic region separating RHO4a and NUD1. From these results we conclude that the proposed RNC1 gene is the result of a cloning artefact and that the yNucR protein is instead encoded by the NUD1 gene.