Featured Research

from universities, journals, and other organizations

Structure Of Important Cell Proteins Described For The First Time

Date:
December 16, 1998
Source:
University Of Georgia
Summary:
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.

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. SNARE stands for soluble N-ethylmaleimide sensitive fusion attachment protein receptor.)

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.

"Our results suggest that v-SNAREs and t-SNAREs from yeast are highly alpha helical," said Lipscomb. "Mechanisms of protein transport and structures of v- and t-SNAREs are believed to be similar among eukaroytic organelles, so our results may reveal general features of these important proteins."

In other words, these proteins are coiled, and each has a region with a high propensity to wrap around its target protein like a snake wrapping around a limb.

Uncovering these structures is an important step forward for Lipscomb in understanding just how these transport proteins work. Before her work, researchers had speculated that these proteins folded in a rather unstructured way and only "knotted up" after they had interacted. Instead, Lipscomb found that both the v-SNAREs and t-SNAREs are already helical. Because this winding structure was heretofore unknown, scientists may have been off base is describing how they worked.

While the new information on these proteins is important, a number of questions about them remain unresolved. Researchers have found that the elimination of the gene that controls the v-SNARE proteins kills the cells, and so the proteins may have secondary and thus far unknown functions.

Lipscomb's laboratory designed an expression system so the scientists would have enough of the proteins to study. They used a common expression system using a bacterium called E. coli to serve as a host to the proteins, which are expressed as the bacterium grows.

Unfortunately, making v-SNARE crystals for study has proved elusive. Lipscomb has doubts now that v-SNAREs can be crystallized, though she holds out some hope for t-SNAREs.

"The good thing is that we can learn a lot about v-SNAREs from t-SNARES," she said. "There doesn't seem to be a lot of homology in the genetic sequences between them, but we strongly suspect that there are structural similarities."


Story Source:

The above story is based on materials provided by University Of Georgia. Note: Materials may be edited for content and length.


Cite This Page:

University Of Georgia. "Structure Of Important Cell Proteins Described For The First Time." ScienceDaily. ScienceDaily, 16 December 1998. <www.sciencedaily.com/releases/1998/12/981216075556.htm>.
University Of Georgia. (1998, December 16). Structure Of Important Cell Proteins Described For The First Time. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/1998/12/981216075556.htm
University Of Georgia. "Structure Of Important Cell Proteins Described For The First Time." ScienceDaily. www.sciencedaily.com/releases/1998/12/981216075556.htm (accessed August 1, 2014).

Share This




More Health & Medicine News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com
House Republicans Vote to Sue Obama Over Healthcare Law

House Republicans Vote to Sue Obama Over Healthcare Law

Reuters - US Online Video (July 31, 2014) The Republican-led House of Representatives votes to sue President Obama, accusing him of overstepping his executive authority in making changes to the Affordable Care Act. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Uganda on Alert for Ebola but No Confirmed Cases

Uganda on Alert for Ebola but No Confirmed Cases

AFP (July 31, 2014) Uganda's health minister said on Thursday that there are no confirmed cases of Ebola in the country, but that it remained on alert for cases of the deadly virus. Uganda has suffered Ebola outbreaks in the past, most recently in 2012. Duration: 00:59 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins