Wednesday, July 25, 2012
Fun Fact: For Neurotransmitter Release, Two Competing Hypotheses Are Both Proven True
For several years now there has been evidence that neurotransmitter release in the brain synapse has been mediated by either one or three SNAREs, which are protein complexes that are involved in membrane fusion. Neurotransmitters are carried in vesicles to the post synaptic neuron, where the vesicle fuses with the neuronal membrane, releasing the neurotransmitters. There has been evidence that only one SNARE is needed for membrane fusion and evidence that three SNAREs are needed for neurotransmitter release.
As it turns out, both pieces of evidence are correct in their finding. Using a new system to experiment with fusion pores, nanodisc membranes were created from lipid bilayers and scaffold proteins, then were combined with SNAREs. Fusion pores are transient events that occur in microseconds and are hard to study. Because of the size of this new nanodisc system, a fusion pore can form and open, but it does not expand larger than 2 nm, thereby capturing the pore in the mid process. By varying the number of SNAREs on the nanodiscs, the researchers were able to determine that only one SNARE per disc was necessary to open a fusion pore, but three SNAREs or more were needed to keep the pore open to allow neurotransmitter release.
Read more about this research here: http://the-scientist.com/2012/07/01/snares-at-the-synapse/?goback=%2Egde_981067_member_136192283
Or read the paper http://www.sciencemag.org/content/335/6074/1355.