A team of neuroscientists led by University of Illinois at Chicago biology professor Simon Alford report the finding in the March 14 issue of the Proceedings of the National Academy of Sciences.
"Until recently, the neuroscience field was solidly behind the idea that these little packets, or vesicles, either released all or none of their neurotransmitter into the synaptic cleft," said Alford. "We've identified a specific molecular mechanism that targets the machinery that causes the fusion process and found that instead of an all-or-none release, the vesicle just kisses the cell's presynaptic membrane. Neuroscientists call it 'kiss and run.' When it does it, our lab has now shown that only a little bit of neurotransmitter is released.
"This is important for the cell because it implies that we can change the degree of information that's passed through the synapse every time it's fired," said Alford.
The process involves a receptor protein on a pre-synaptic nerve cell -- the side that fires the packet of neurotransmitter -- that is affected by 5-hydroxytryptamine, or 5-HT, a body chemical often associated with mood. When 5-HT binds to this cell receptor, it activates something called a G protein that is made of two subunits -- one called alpha, the other beta-gamma. When these subunits are released, they activate the next step in a chain of events that move signal information through the nerve cell.
Alford's lab previously discovered that the beta-gamma subunit affects the molecular machinery that causes release of neurotransmitter -- the amino acid glutamate.
"It's very fast," said Alford. "You turn on a G protein, and it immediately targets the mechanism to modify release."
On the receiving cell, the p
Source:University of Illinois at Chicago