CONSIDERATION OF THE EVOLUTION OF THE SACCHAROMYCES-CEREVISIAE MEL GENE FAMILY ON THE BASIS OF THE NUCLEOTIDE-SEQUENCES OF THE GENES AND THEIR FLANKING REGIONS

Analysis of the DNA sequences of new members of the Saccharomyces cere visiae MEL1-MEL10 gene family showed high homology between the members . The MEL gene family, alpha-galactosidase-coding sequences, have dive rged into two groups; one consisting of MEL1 and MEL2 and the other of MEL3-MEL10. In two S. cerevisiae strains containing five or seven MEL genes each, all the genes are nearly identical, suggesting very rapid distribution of the gene to separate chromosomes. The sequence homolo gy and the abrupt change to sequence heterogeneity at the centromere-p roximal 3' end of the MEL genes suggest that the distribution of the g enes to new chromosomal locations has occurred partly by reciprocal re combination at solo delta sequences. We identified a new open reading frame sufficient to code for a 554 amino acid long protein of unknown function. The new open reading frame (Accession number Z37509) is loca ted in the 3' non-coding region of MEL3-MEL10 genes in opposite orient ation to the MEL genes (Accession numbers Z37508, Z37510, Z37511). Nor thern analysis of total RNA showed no hybridization to a homologous pr obe, suggesting that the gene is not expressed efficiently if at all.