MAPPING AND SEQUENCING OF 2 YEAST GENES BELONGING TO THE ATP-BINDING CASSETTE SUPERFAMILY

ATP-binding cassette (ABC) transporters share significant sequence ide ntity within their ATP-binding domains. Degenerate oligonucleotides ba sed on highly conserved portions of the ATP-binding domain genes were used to clone portions of two members of the ABC gene superfamily from Saccharomyces cerevisiae DNA. These genes were designated MDL1 and MD L2 (for multidrug resistance-like). Each MDL gene is predicted to enco de a single set of transmembrane domains and a single ATP-binding doma in, thus the MDL gene products are 'half-molecule' ABC proteins. The t wo genes were mapped to precise regions on chromosomes XII and XVI and show a considerable similarity to the mammalian P-glycoprotein/multid rug resistance (MDR) and peptide transporter (TAP) genes. Preliminary analysis of null mutants constructed by gene replacement has indicated that the MDL genes are not essential for viability of yeast. The sequ ences have been deposited in the GenBank data library under Accession Numbers L16958 (Locus YSCBCSA) and L16959 (Locus YSCBCSB).