Our research is devoted to a molecular description of the process of membrane assembly and vesicular traffic in eukaryotic cells. Basic principles that emerged from these studies in yeast are now being applied to studies of genetic diseases of protein transport.
A combination of genetic and cytologic evaluation of the secretion (sec) mutants has allowed a description of the secretory pathway in Saccharomyces cerevisiae. Protein transport in yeast appears to be mediated by the same organelles and proteins that operate in mammalian cells. Molecular cloning analysis of SEC genes revealed striking structural and functional homology with corresponding mammalian genes.
We have developed biochemical assays that measure the early events of polypeptide translocation into the endoplasmic reticulum (ER) and of vesicle-mediated protein transport from the ER to the Golgi apparatus. Sec61p forms the channel in the ER membrane through which secretory polypeptides pass from the cytoplasm into the lumen. Misfolded secretory proteins are removed from the ER by reverse translocation, though the channel responsible for this process remains to be clearly identified. The transport of secretory and membrane cargo proteins is mediated by diffusible vesicles. The formation of these vesicles in vitro depends on the Sec proteins that were predicted to be involved from genetic and morphological inspection of sec mutant cells. Isolated transport vesicles contain membrane and internal proteins that are targeted to other compartments in the cell, but they are nearly devoid of proteins that are located in the ER. Thus, the budding mechanism somehow distinguishes transported from ER-resident proteins. This sorting and budding process is highly evolutionarily conserved; mammalian equivalents of the yeast Sec proteins have been isolated and are known to operate in the same location within the cell.
For more detailed information on general areas of research within the lab, see the following pages. In addition, each researcher has a short synopsis of their own specific research interest on the Lab Members page.
Analysis of Vesicle Budding from the ER
Traffic in Human Genetic Diseases
Vesicle Traffic Late in the Secretory Pathway
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