Heterologous Expression of Syntaxin 6 in Saccharomyces cerevisiae

the molecular mechanisms of vesicular protein transport in eukaryotic cells are highly conserved. members of the syntaxin family play a pivotal role in the membrane fusion process. we have expressed rat syntaxin 6 and its cytoplasmic domain in wild-type and pep12 mutant strains of saccharomyces cerevisiae to elucidate the role of the syntaxin 6-dependent vesicular trafficking step in yeast. immunofluorescence microscopy revealed a punctate, golgi-like staining pattern for syntaxin 6, which only partially overlapped with pep12p in wild-type yeast cells. in contrast to pep12p, syntaxin 6 was not mislocalized to the vacuole upon expression from 2 micron vectors, which might be attributed to conserved sorting and retention signals. syntaxin 6 was not capable of complementing the sorting and maturation defects of the vacuolar hydrolase cpy in pep12 null mutants. no dominant negative effects of either syntaxin 6 or syntaxin 6dc overexpression on cpy sorting and maturation were observed in wild-type yeast cells. we conclude that syntaxin 6 and pep12p do not act at the same vesicular trafficking step(s) in yeast and higher eukaryotes