英和和英

出典:『Wikipedia』 (2011/05/24 21:20 UTC 版)

英語による解説

引用

The active zone is a term first used by Couteaux and Pecot-Dechavassinein in 1970 and is defined in the neuron as the site of neurotransmitter release. Neurons contain structures called synapses that allow for the communication from one neuron to another. These synapses like the one diagrammed on the right contain a structure (top of picture) called a presynaptic bouton that stores vesicles containing neurotransmitter and releases the contents of those vesicles upon the arrival of an action potential. This neurotransmitter released by the presynaptic neuron then travels to the postsynaptic neuron (neuron on bottom) and activates receptors on the membrane of this neuron. The active zone is a region in the presynaptic bouton that mediates neurotransmitter release and is composed of the presynaptic membrane and a dense collection of proteins called the cytomatrix at the active zone (CAZ). The CAZ is identified in a electron microscope as a darkened (electron dense) area close to the presynaptic membrane. The proteins within the CAZ tether synaptic vesicles to the presynaptic membrane and mediate synaptic vesicle fusion to allow for neurotransmitter release. The machinery within the CAZ ensures that synaptic vesicles will be reliably and rapidly released upon the arrival of an action potential.