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 synapses 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 human genetics at BCM (http://flypush.imgen.bcm.tmc.edu/lab/), 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 calcium channel.
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 protein 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."
Bellen is director of the BCM program in developmental biology and a Howard Hughes Medical Institute investigator.
Others who took part in this research include Yong Qi Lin, Cindy V. Ly, Tomoko Ohyama, Claire M. Haueter, Vera Y. Moiseenkova-Bell and Theodore G. Wensel, all of BCM.
Funding for this work came from the National Institute of Neurological Diseases and Stroke, the BCM Intellectual and Developmental Disabilities Research Center and the Howard Hughes Medical Institute.
When the embargo lifts, this report will be available at www.cell.com.
For more information on basic science research at Baylor College of Medicine, go to www.bcm.edu/fromthelab or www.bcm.edu/news.
Glenna Picton | EurekAlert!
Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover
First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences