TY - JOUR
T1 - Nucleotide sequence of the yeast STE14 gene, which encodes farnesylcysteine carboxyl methyltransferase, and demonstration of its essential role in a-factor export
AU - Sapperstein, Stephanie
AU - Berkower, Carol
AU - Michaelis, Susan
PY - 1994/2
Y1 - 1994/2
N2 - Eukaryotic proteins initially synthesized with a C-terminal CAAX motif (C is Cys, A is aliphatic, and X can be one of several amino acids) undergo a series of modifications involving isoprenylation of the Cys residue, proteolysis of AAX, and α-carboxyl methyl esterification of the newly formed isoprenyl cysteine. We have previously demonstrated that STE14 encodes the enzyme which mediates carboxyl methylation of the Saccharomyces cerevisiae CAAX proteins a-factor, RAS1, and RAS2. Here we report the nucleotide sequence of STE14, which indicates that STE14 encodes a protein of 239 amino acids, predicted to contain multiple membrane-spanning segments. Mapping data indicate that STE14 resides on chromosome IV, tightly linked to ADE8. By analysis of ste14 null alleles, we demonstrated that MATa ste14 mutants are unable to mate but are viable and exhibit no apparent growth defects. Additional analysis of ste14 ras1 and ste14 ras2 double mutants, which grow normally, reinforces our previous conclusion that RAS function is not significantly influenced by its methylation status. We examine a-factor biogenesis in a ste14 null mutant by metabolic labeling and immunoprecipitation and demonstrate that although proteolytic processing and membrane localization of a-factor are normal, the ste14 null mutant exhibits a profound block in a-factor export. This observation suggests that the methyl group is likely to be a critical recognition determinant for the a- factor transporter, STE6, thus providing insight into the substrate specificity of STE6 and also supporting the hypothesis that carboxyl methylation can have a dramatic impact on protein-protein interactions.
AB - Eukaryotic proteins initially synthesized with a C-terminal CAAX motif (C is Cys, A is aliphatic, and X can be one of several amino acids) undergo a series of modifications involving isoprenylation of the Cys residue, proteolysis of AAX, and α-carboxyl methyl esterification of the newly formed isoprenyl cysteine. We have previously demonstrated that STE14 encodes the enzyme which mediates carboxyl methylation of the Saccharomyces cerevisiae CAAX proteins a-factor, RAS1, and RAS2. Here we report the nucleotide sequence of STE14, which indicates that STE14 encodes a protein of 239 amino acids, predicted to contain multiple membrane-spanning segments. Mapping data indicate that STE14 resides on chromosome IV, tightly linked to ADE8. By analysis of ste14 null alleles, we demonstrated that MATa ste14 mutants are unable to mate but are viable and exhibit no apparent growth defects. Additional analysis of ste14 ras1 and ste14 ras2 double mutants, which grow normally, reinforces our previous conclusion that RAS function is not significantly influenced by its methylation status. We examine a-factor biogenesis in a ste14 null mutant by metabolic labeling and immunoprecipitation and demonstrate that although proteolytic processing and membrane localization of a-factor are normal, the ste14 null mutant exhibits a profound block in a-factor export. This observation suggests that the methyl group is likely to be a critical recognition determinant for the a- factor transporter, STE6, thus providing insight into the substrate specificity of STE6 and also supporting the hypothesis that carboxyl methylation can have a dramatic impact on protein-protein interactions.
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U2 - 10.1128/MCB.14.2.1438
DO - 10.1128/MCB.14.2.1438
M3 - Article
C2 - 8289819
AN - SCOPUS:0028125792
SN - 0270-7306
VL - 14
SP - 1438
EP - 1449
JO - Molecular and cellular biology
JF - Molecular and cellular biology
IS - 2
ER -