Cell Biology
Genetics is the key to understanding the role that coat proteins play in sorting and packaging protein cargo for transport, said Randy Schekman, chair of the Department of Molecular and Cell Biology at the University of California, Berkeley, during the biennial Fawcett Lecture at HMS on May 28.
Following an introduction by Marc Kirschner, head of the HMS Department of Cell Biology, Schekman reviewed the research leading up to his recent work with COPII, a protein that drives vesicle formation.
Schekman studies protein secretion in test tubes, reconstituting the elements of the budding reaction in the yeast Saccharomyces cerevisiae to see how vesicles dock, fuse, and deliver their proteins.
"I figured one way to really solve the problem would be a cell-free system," he said. "My conviction is that biochemistry is an important follow through to cell biology and that it is possible to combine yeast genetics and biochemistry to study membrane traffic."
Along with his colleagues at Berkeley, Schekman was the first to recognize that the secretory process could be dissected using S. cerevisiae as a model. He developed yeast that were defective for a set of genes called sec, which are required for protein transport. These genes could be turned on and off by altering the temperature, thereby stopping at will the transport of proteins from the cytosol into the endoplasmic reticulum, the sorting of proteins within the Golgi, and the transport of secretory vesicles to the plasma membrane.
Understanding the role of coat proteins may provide insight into some human diseases, Schekman said. For example, he is interested in proteins associated with Alzheimer's disease, because the amyloid plaques that accumulate outside nerve cells may be secreted unnecessarily, causing brain degeneration.
--Cassie Ferguson
Focus 7/17/98