Mutational analysis of the role of N-glycosylation in alpha-factor receptor function

Biochemistry. 2001 Aug 14;40(32):9685-94. doi: 10.1021/bi0108507.


The alpha-factor mating pheromone receptor (encoded by STE2) activates a G protein signaling pathway that stimulates the conjugation of Saccharomyces cerevisiae yeast cells. The alpha-factor receptor is known to undergo several forms of post-translational modification, including phosphorylation, mono-ubiquitination, and N-linked glycosylation. Since phosphorylation and mono-ubiquitination have been shown previously to play key roles in regulating the signaling activity and membrane trafficking of the alpha-factor receptors, the role of N-linked glycosylation was investigated in this study. The Asn residues in the five consensus sites for N-linked glycosylation present in the extracellular regions of the receptor protein were mutated to prevent carbohydrate attachment at these sites. Mutation of two sites near the receptor N-terminus (N25Q and N32Q) diminished the degree of receptor glycosylation, and the corresponding double mutant was not detectably N-glycosylated. The nonglycosylated receptors displayed normal function and subcellular localization, indicating that glycosylation is not important for wild-type receptor activity. However, mutation of the glycosylation sites resulted in improved plasma membrane localization for the Ste2-3 mutant receptors that are normally retained intracellularly at elevated temperatures. These results suggest that N-glycosylation may be involved in the sorting process for misfolded Ste2 proteins, and may similarly affect certain mutant receptors whose altered trafficking is implicated in human diseases.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • DNA Mutational Analysis
  • Genes, Reporter
  • Glycosylation
  • Humans
  • Immunoblotting
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Structure, Secondary
  • Receptors, Mating Factor
  • Receptors, Peptide / chemistry
  • Receptors, Peptide / genetics
  • Receptors, Peptide / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / physiology*
  • Transcription Factors*


  • Receptors, Mating Factor
  • Receptors, Peptide
  • Recombinant Fusion Proteins
  • Transcription Factors