Synapsin

Drug Details

Synapsins are a family of neuron-specific proteins that play a crucial role in the regulation of neurotransmitter release at synapses. They are among the most abundant proteins in the brain, comprising approximately 1% of total brain protein. Synapsins are primarily associated with the membranes of synaptic vesicles within the presynaptic terminal, where they help tether these vesicles to the actin cytoskeleton, forming a reserve pool. This tethering is essential for maintaining an adequate supply of vesicles ready for neurotransmitter release. Upon neuronal stimulation, synapsins undergo phosphorylation, leading to their dissociation from synaptic vesicles and the cytoskeleton. This process allows the vesicles to move toward the presynaptic membrane, facilitating the release of neurotransmitters into the synaptic cleft. In mammals, there are three synapsin genes—Synapsin I, Synapsin II, and Synapsin III—each producing multiple isoforms through alternative splicing. These isoforms have distinct but overlapping functions in synaptic transmission and plasticity. Notably, mutations or alterations in synapsin genes have been linked to various neurological disorders, including epilepsy, schizophrenia, and bipolar disorder, highlighting their importance in maintaining normal brain function.