Second messengers, phosphorylation and neurotransmitter release

It is well established that the release of neurotransmitters is initiated by the influx of Ca²⁺ through voltage sensitive calcium channels in the nerve terminal. However, exactly what transpires biochemically following Ca²⁺ entry is rather mysterious. Recent biochemical and biophysical data relating to the protein synapsin I have increased our understanding of the processes involved. Other related studies have suggested further sites at which the release process can be modulated by neurotransmitters and drugs. Several of these possibilities are discussed in this article.