THE DNA-SEQUENCE ANALYSIS OF THE HAP4-LAP4 REGION ON CHROMOSOME-XI OFSACCHAROMYCES-CEREVISIAE SUGGESTS THE PRESENCE OF A 2ND 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 expe cted HAP4, GFA1 and LAP4 genes have been found and six new open readin g frames (ORFs) with a coding capacity of more than 100 amino acid res idues have been identified. One of them (YKL461) shows a high degree o f identity with an aspartate aminotransferase gene. This raises the qu estion 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.