How does calcium cause exocytosis?

In neuronal cells, calcium is instrumental in stimulating synaptic vesicle exocytosis and the release of neurotransmitters such as ATP. When a presynaptic action potential arrives at a nerve terminal it activates voltage-gated calcium channels which cause an increase in intracellular calcium at the active zone. This influx of calcium into the terminal triggers exocytosis.

In endocrine cells, calcium triggers large dense-core vesicle (LDCV) exocytosis and the release of hormones.