ISOLATION AND DNA-SEQUENCE OF THE STE14 GENE ENCODING FARNESYL CYSTEINE - CARBOXYL METHYLTRANSFERASE

We isolated a mutant defective in C-terminal farnesyl cysteine:carboxy l methyltransferase activity from a screen for mutations causing a-spe cific sterility. A genomic fragment was cloned from a yeast multi-copy library that restored mating. Both the cloned gene and the sterile mu tation were allelic to the STE14 gene. A ste14-complementing 2.17 kb B amHI fragment subclone was sequenced and found to encode a 239 amino a cid protein with a molecular weight of 27,887 Daltons. The hydrophobic ity profile of the methyltransferase reveals the presence of at least five potential transmembrane domains. In comparisons of the C-terminal methyltransferase amino acid sequence with those in the PIR and Swiss protein databases, no significantly similar sequences were found nor were conserved regions from other methyltransferases present.