Synaptotagmin is a protein found in the membranes of synaptic vesicles in neurons. It plays a crucial role in the process of neurotransmitter release, acting as a calcium sensor. When calcium ions enter the neuron, synaptotagmin binds to them, triggering the fusion of synaptic vesicles with the cell membrane and allowing neurotransmitters to be released into the synaptic cleft. This release of neurotransmitters is essential for communication between neurons, influencing various functions in the nervous system. Synaptotagmin is part of a larger family of proteins involved in synaptic transmission, highlighting its importance in the overall functioning of the brain.