Gene called flower missing link in vesicle uptake in neurons

September 3, 2009

As part of the intricate ballet of synaptic transmission from one neuron to the next, tiny vesicles - bubbles containing the chemical neurotransmitters that make information exchange possible -- travel to the tip of neurons (synapses), where they fuse with the cell's membrane (a process called exocytosis).

The extra membrane is then captured in a process called endocytosis and recycled to form a new vesicle to enable the next cycle of release. Most important, exocytosis must be tightly coupled with endocytosis to sustain rapid neurotransmission, said researchers from Baylor College of Medicine in a report that appears in this week's issue of the journal Cell.

Calcium influx into the through tiny pores or channels in the membrane initiates the release of vesicles via exocytosis. Since neurons can fire impulses as frequently as 500 times a second, the calcium that flows into the synapses must be removed very rapidly to keep the process going.

After exocytosis, the vesicle membranes must be retrieved, and this process is also stimulated by an increase in calcium in the synapses, but the channel that mediates this influx was unknown until Dr. Hugo Bellen, a professor of molecular and at BCM, and his colleagues identified it in an elegant series of experiments. Interestingly, this channel is present in the vesicles. Hence, the vesicles carry the means to activate their own re-uptake in the form of a protein that functions as a .

A genetic screen identified a novel gene called flower, and Chi-Kuang Yao, a postdoctoral fellow in Bellen's laboratory, mapped the gene and showed that the corresponding protein is present in the membrane of synaptic vesicles. He then showed that fruit flies lacking this gene were less able to endocytose vesicles.

Direct experiments involved purifying the Flower protein, putting it into liposomes or artificial vesicles and showing that several copies of the protein can aggregate together and form a channel in membranes. When calcium was introduced into this system, it could enter the vesicle, showing that the allows calcium entry.

"The vesicle carries its own channel to promote endocytosis," said Bellen. "It is a simple regulatory system. The mechanism links exocytosis and endocytosis."

Source: Baylor College of Medicine (news : web)

Explore further: Viewing dye-packed vesicles causes them to explode

Related Stories

Viewing dye-packed vesicles causes them to explode

September 25, 2007

It’s a long-standing question: Can just the act of observing an experiment affect the results? According to a new study by Rockefeller University scientists, if the experiment uses a fluorescent dye called acridine orange, ...

Cells use import machinery to export their goods as well

July 3, 2009

( -- In the bustling economy of the cell, little bubbles called vesicles serve as container ships, ferrying cargo to and from the port — the cell membrane. Some of these vesicles, called post-Golgi vesicles, ...

Protein 'Tweek' rare but critical in synaptic process

July 29, 2009

(July 29, 2009) - Recycling is a critical component in the process of transmitting information from one neuron to the next, and a large protein called Tweek plays a critical role, said an international consortium of researchers ...

Recommended for you

Study suggests fish can experience 'emotional fever'

November 25, 2015

(—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...

Winter season reverses outcome of fruit fly reproduction

November 24, 2015

Male fruit flies could find their chances of fathering offspring radically reduced if they are last in the queue to mate with promiscuous females before winter arrives, according to new University of Liverpool research.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.