Featured Research

from universities, journals, and other organizations

Molecular Motor Shuttles Key Protein In Response To Light

Date:
July 19, 2004
Source:
Johns Hopkins Medical Institutions
Summary:
In experiments with fruit flies, Johns Hopkins researchers have discovered how a key light-detecting molecule in the eye moves in response to changes in light intensity.

In experiments with fruit flies, Johns Hopkins researchers have discovered how a key light-detecting molecule in the eye moves in response to changes in light intensity.

Related Articles


Their finding adds to growing evidence that some creatures -- and probably people -- adapt to light not only by mechanically shrinking the pupil to physically limit how much light enters the eye, but also by a chemical response.

Building on their previous work showing that specific proteins in eye cells are redistributed in response to bright light, the Johns Hopkins team now reports how a key protein called arrestin is shuttled from a "holding area" where it binds and calms a light-detecting protein. Writing in the July 7 issue of Neuron, the team says arrestin is moved around by a tiny molecular motor, called myosin, which travels along the "train tracks" of the cell's internal skeleton.

Arrestin's swift relocation, the researchers proposed, helps prevent temporary blindness that would otherwise be caused by a sudden increase in light intensity, such as occurs when stepping from a dark movie theater into the bright afternoon sunshine.

"We knew that arrestin was transported, but we didn't know how this occurred," says Craig Montell, Ph.D., professor of biological chemistry. "Fly and mammalian eyes have similar light detector cells and proteins, and it takes about the same amount of time for our eyes to adapt to light, so we suspect that comparable mechanisms exist in humans."

The light-detecting cells in fruit flies are similar to the rod and cone cells found in the human retina. One end of each cell contains the protein that directly responds to light, but other proteins critical for the light response are shifted back and forth into different parts of the cell in a light-dependent manner. Scientists didn't know how these molecules might be moved from one end of the cell to the other, until now.

Postdoctoral fellow Seung-Jae Lee, Ph.D., had a hunch that myosin -- a molecular motor -- might play a role in transporting arrestin. Studying flies that had been engineered to lack a myosin, dubbed NINAC for "neither inactivation nor afterpotential C," Lee found that arrestin didn't move when the fly was exposed to bright light. Instead, arrestin stayed in the protein-making part of the cell.

"For the cell to properly adapt to bright light, arrestin needs to move," says Montell. "If it doesn't, the cell remains as sensitive to light as it was when it was dark."

While some details of arrestin's shuttling in flies are still unclear, the researchers showed that arrestin and the motor don't bind to each other directly. Instead, they are "glued" together by a sticky fat, called phosphoinositides.

"Arrestin is pasted onto the myosin motor and is quickly taken to its target destination within the cell," says Montell. "This explains why it moves much faster than if it just moved passively, essentially wandering to the other side of the cell."

The researchers will now study mice to see if there are similar chemical controls of light adaptation. They will also start examining other proteins that move in response to light in both flies and mice.

The research was supported by the National Eye Institute. Authors on the paper are Lee and Montell. Lee is now a postdoctoral fellow in the Department of Biochemistry and Biophysics at the University of California, San Francisco.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Cite This Page:

Johns Hopkins Medical Institutions. "Molecular Motor Shuttles Key Protein In Response To Light." ScienceDaily. ScienceDaily, 19 July 2004. <www.sciencedaily.com/releases/2004/07/040719090318.htm>.
Johns Hopkins Medical Institutions. (2004, July 19). Molecular Motor Shuttles Key Protein In Response To Light. ScienceDaily. Retrieved April 18, 2015 from www.sciencedaily.com/releases/2004/07/040719090318.htm
Johns Hopkins Medical Institutions. "Molecular Motor Shuttles Key Protein In Response To Light." ScienceDaily. www.sciencedaily.com/releases/2004/07/040719090318.htm (accessed April 18, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, April 18, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Our Love Of Puppy Dog Eyes Explained By Science

Our Love Of Puppy Dog Eyes Explained By Science

Newsy (Apr. 17, 2015) Researchers found a spike in oxytocin occurs in both humans and dogs when they gaze into each other&apos;s eyes. Video provided by Newsy
Powered by NewsLook.com
Scientists Find Link Between Gestational Diabetes And Autism

Scientists Find Link Between Gestational Diabetes And Autism

Newsy (Apr. 17, 2015) Researchers who analyzed data from over 300,000 kids and their mothers say they&apos;ve found a link between gestational diabetes and autism. Video provided by Newsy
Powered by NewsLook.com
Video Messages Help Reassure Dementia Patients

Video Messages Help Reassure Dementia Patients

AP (Apr. 17, 2015) Family members are prerecording messages as part of a unique pilot program at the Hebrew Home in New York. The videos are trying to help victims of Alzheimer&apos;s disease and other forms of dementia break through the morning fog of forgetfulness. (April 17) Video provided by AP
Powered by NewsLook.com
Boy or Girl? Intersex Awareness Is on the Rise

Boy or Girl? Intersex Awareness Is on the Rise

AP (Apr. 17, 2015) At least 1 in 5,000 U.S. babies are born each year with intersex conditions _ ambiguous genitals because of genetic glitches or hormone problems. Secrecy and surgery are common. But some doctors and activists are trying to change things. (April 17) 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:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

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