ATHENS, Ga. -- Like commuters pushing onto a train, certain proteins in cells always have a ticket to ride. They move through small cavities called vesicles from one place to another so that certain crucial biochemical tasks can take place. These vesicles bud off specialized and organ-like cell parts called organelles, carrying their protein passengers to another site in the cell.
This elegant catch and release keeps a proper protein level in organelles so they can keep working in the cell. Scientists at the University of Georgia have, for the first time, described the shape of two important yeast proteins that make such transport possible in eukaryotic cells -- those with well-defined nuclei.
"The goal of our laboratory is to understand the structural basis of docking and fusion at the molecular level," said Dr. Leigh Ann Lipscomb, an assistant professor of biochemistry. Lipscomb presented her findings at the Protein Society meeting in San Diego earlier this year.
Here's how it works in yeast, the organism Lipscomb is studying. The cell releases the vesicles with their protein "passengers" in a process called budding. After budding, an interaction between proteins on the surface of the vesicle and the target organelle leads the "train" to its station where it fuses with the organelle and delivers its proteins. (Two proteins are involved, v-SNARE, which is in the vesicle, and t-SNARE, which is on the target organelle.*)
The question scientists had not unraveled was exactly what structure these two proteins have in eukaryotic cells -- a crucial factor in understanding how they work. Only recently have the structures of two mammalian SNARE proteins been described, but presently no x-ray or nuclear magnetic resonance structures are available for these structures in yeast, so Lipscomb and her colleagues used several techniques, including infrared spectroscopy, to study the proteins.
"
'"/>
Contact: Phil Williams
philwpio@arches.uga.edu
706-542-8501
University of Georgia
11-Dec-1998