The DNA sequence analysis of the HAP4–LAP4 region on chromosome XI of Saccharomyces cerevisiae suggests the presence of a second aspartate aminotransferase gene in yeast

The nucleotide sequence of a 19 000 base pair region from the left arm of chromosome XI of Saccharomyces cerevisiae has been determined and analysed. It covers the HAP4–GFA1–LAP4 loci already described. As expected HAP4, GFA1 and LAP4 genes have been found and six new open reading frames (ORFs) with a coding capacity of more than 100 amino acid residues have been identified. One of them (YKL461) shows a high degree of identity with an aspartate aminotransferase gene. This raises the question of a second aspartate aminotransferase gene in yeast. A second ORF (YKL462) shows features compatible with a membranous localization. The other ORFs do not show a similarity with any known gene. A member of the highly repetitive ‘CAT’ DNA sequence is present.