Featured Research

from universities, journals, and other organizations

Neurotransmission Machinery Visualized For The First Time

Date:
September 24, 1998
Source:
Howard Hughes Medical Institute
Summary:
The classic image of communication between brain cells shows a neurotransmitter crossing the synapse and binding to receptors on the surface of a neighboring neuron. Yet, scientists have had only a murky picture of the events within the secreting neuron that trigger this neurotransmitter release.

September 23,1998—The classic image of communication between brain cells shows a neurotransmitter crossing the synapse and binding to receptors on the surface of a neighboring neuron. Yet, scientists have had only a murky picture of the events within the secreting neuron that trigger this neurotransmitter release.

Now, a group of researchers led by Axel T. Brunger, a Howard Hughes Medical Institute (HHMI) investigator at Yale University has deciphered and produced the first glimpses of the molecular machinery that propels neurotransmitters into the synapse. The key players are a family of proteins called SNAREs (Soluble NSF Attachment protein REceptor). These proteins haven't changed much through evolution; SNAREs play a similar role in the secretions of even primitive life forms like yeast.

In neurons, the merging of these mostly amorphous proteins into a highly structured and charged complex precipitates neurotransmitter release. Formation of the complex fuses vesicles—tiny sacs carrying the neurotransmitter inside the neuron—with the cell membrane, spewing the neurotransmitter into the synapse. Such vesicle fusion occurs millions of times daily in each of the human brain's 100 billion neurons. So understanding vesicle fusion promises to shed light on processes like learning and memory, and may lead to improved treatments for brain disorders.

"It's sort of like merging two soap bubbles into one, but hardly that simple," explained R. Bryan Sutton, an HHMI associate in Brunger's laboratory. Sutton, Brunger and their colleagues report the elucidation of the synaptic fusion complex's intricate molecular structure in the September 24, 1998, issue of Nature.

The researchers used ultra-bright x-ray radiation from a synchrotron facility funded by the U.S. Department of Energy to illuminate the tiny protein crystals and determine the shape of the complex, atom-by-atom. They then created computer reconstructions that provide clues about how this pivotal protein may accomplish its mission.

Within the neuron, vesicles fill up with neurotransmitters, such as dopamine or serotonin. They then travel out into the neuron's extensions (axons), where they dock at the membrane and await an electrochemical signal to merge. At this moment the SNAREs form a complex.

Like other known fusion mechanisms, such as those used by viruses to infect cells, synaptic fusion employs a protein agent to meld two membranes. But unlike viral mechanisms, in which the fusion protein simply changes its shape, the very assembly of the synaptic fusion protein itself leads to the union of vesicle and cell membrane.

This assembly likely begins when two SNARE proteins in the cell's membrane, SNAP-25 and syntaxin, join together, Brunger says. This two-part complex is then joined by a third protein from the vesicle, synaptobrevin, in a configuration that sets up electrical and chemical forces that could promote membrane fusion. In addition, highly flexible helical structures in the complex, prone to twisting and bending, could cause strains that physically deform fatty layers within the two membranes, allowing them to mix. The complex's highly grooved surface, with distinct electrically and chemically polarized regions, could also be important for fusion and for the binding of regulatory factors affecting neurotransmission, say the researchers.

"The complex may act sort of like a winch to drive the vesicle down into the neuron's membrane," said Brunger. "Diseases such as tetanus and botulism take advantage of the fusion machinery by attacking these ties between neurotransmitter-filled vesicles and the neuron's membrane, effectively cutting the winch cable and causing neurological symptoms."

Advances in knowledge about the protein complex's structure could be of potential use in designing new medications for disorders of brain function, suggests Brunger.


Story Source:

The above story is based on materials provided by Howard Hughes Medical Institute. Note: Materials may be edited for content and length.


Cite This Page:

Howard Hughes Medical Institute. "Neurotransmission Machinery Visualized For The First Time." ScienceDaily. ScienceDaily, 24 September 1998. <www.sciencedaily.com/releases/1998/09/980924075145.htm>.
Howard Hughes Medical Institute. (1998, September 24). Neurotransmission Machinery Visualized For The First Time. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/1998/09/980924075145.htm
Howard Hughes Medical Institute. "Neurotransmission Machinery Visualized For The First Time." ScienceDaily. www.sciencedaily.com/releases/1998/09/980924075145.htm (accessed July 29, 2014).

Share This




More Health & Medicine News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Two Americans Contract Ebola in Liberia

Two Americans Contract Ebola in Liberia

Reuters - US Online Video (July 28, 2014) Two American aid workers in Liberia test positive for Ebola while working to combat the deadliest outbreak of the virus ever. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
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