The multispanning membrane protein Ste24p catalyzes CAAX proteolysis and NH2-terminal processing of the yeast a-factor precursor.
Saccharomyces cerevisiae Ste24p is a multispanning membrane protein implicated in the CAAX proteolysis step that occurs during biogenesis of the prenylated a-factor mating pheromone. Whether Ste24p acts directly as a CAAX protease or indirectly to activate a downstream protease has not yet been established. In this study, we demonstrate that purified, detergent-solubilized Ste24p directly mediates CAAX proteolysis in a zinc-dependent manner. We also show that Ste24p mediates a separate proteolytic step, the first NH(2)-terminal cleavage in a-factor maturation. These results establish that Ste24p functions both as a bona fide COOH-terminal CAAX protease and as an a-factor NH(2)-terminal protease. Importantly, this study is the first to directly demonstrate that a eukaryotic multispanning membrane protein can possess intrinsic proteolytic activity.
Tam
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Department of Cell Biology and Anatomy, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Schmidt
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WK
Michaelis
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D000595:Amino Acid Sequence; D002384:Catalysis; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019286:Endopeptidase K / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D005838:Genotype; D013058:Mass Spectrometry; D000072235:Mating Factor; D008565:Membrane Proteins / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism*; D008745:Methylation; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D043484:Proprotein Convertases; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism*; D017368:Protein Prenylation; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology
D003902:Detergents; D008565:Membrane Proteins; D010455:Peptides; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D010450:Endopeptidases; D043484:Proprotein Convertases; D019286:Endopeptidase K; C105193:RCE1 protein, S cerevisiae; D008666:Metalloendopeptidases; C491251:STE24 protein, S cerevisiae; D015032:Zinc