title: The Saccharomyces cerevisiae BAR1 gene encodes an exported protein with homology to pepsin.
abstract: Saccharomyces cerevisiae a cells secrete an extracellular protein, called "barrier" activity, that acts as an antagonist of alpha factor, the peptide mating pheromone produced by mating-type alpha cells. We report here the DNA sequence of BAR1, the structural gene for barrier activity. The deduced primary translation product of 587 amino acids has a putative signal peptide, nine potential asparagine-linked glycosylation sites, and marked sequence similarity of the first two-thirds of the protein with pepsin-like proteases. Barrier activity was abolished by in vitro mutation of an aspartic acid predicted from this sequence homology to be in the active site. Therefore, barrier protein is probably a protease that cleaves alpha factor. The sequence similarity suggests that the first two-thirds of the barrier protein is organized into two distinct structural domains like those of the pepsin-like proteases. However, the BAR1 gene product has a third carboxyl-terminal domain of unknown function; deletion of at least 166 of the 191 amino acids of this region has no significant effect on barrier activity.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D001483:Base Sequence; D003001:Cloning, Molecular; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005796:Genes; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D010434:Pepsin A / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid
chemical_list: D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C491999:BAR1 protein, S cerevisiae; D010434:Pepsin A