| Property | Value |
|---|---|
| Protein Name | Synaptotagmin-2 |
| Gene | SYT2 |
| UniProt ID | Q9H0Y5 |
| Molecular Weight | ~67 kDa (421 aa) |
| Subcellular Localization | Synaptic vesicles, presynaptic terminal |
| Protein Family | Synaptotagmin family |
| Tissue Expression | Brain (neurons), especially cerebral cortex and brainstem |
Synaptotagmin-2 (SYT2) is a member of the synaptotagmin family of calcium-binding proteins that function as fast calcium sensors for synaptic vesicle exocytosis[1]. Unlike other synaptotagmins, SYT2 is specifically adapted for synchronous neurotransmitter release—the fast, millisecond-scale neurotransmitter release that underlies rapid neuronal communication. Mutations in SYT2 cause human neurological disorders including congenital myasthenic syndromes and epilepsy, highlighting its essential role in synaptic function.
SYT2 is expressed primarily in excitatory neurons of the cerebral cortex, hippocampus, and brainstem, where it couples calcium influx through voltage-gated calcium channels to synaptic vesicle fusion. The protein contains two C2 domains that bind calcium with high affinity and specificity, enabling it to function as a precise calcium sensor for neurotransmitter release.
SYT2 contains several key structural features[1:1]:
N-terminal transmembrane region (residues 1-60): Anchors the protein to synaptic vesicle membranes via a single transmembrane helix (type I membrane protein).
Linker region (residues 61-130): Flexible tether connecting the transmembrane region to the C2 domains.
C2A domain (residues 131-270): The first C2 domain that binds calcium with high affinity. This domain interacts with the SNARE complex.
C2B domain (residues 271-421): The second C2 domain that binds calcium and mediates interactions with phospholipids and proteins.
SYT2 functions as a calcium sensor through its C2 domains:
The calcium dissociation rate (~10,000/s) matches the time scale of synchronous release, making SYT2 an ideal fast calcium sensor.
SYT2 triggers synaptic vesicle fusion through several mechanisms[1:2]:
SYT2 is essential for fast synchronous neurotransmission:
SYT2 contributes to presynaptic organization:
SYT2 expression patterns define specific neuronal circuits:
SYT2 alterations contribute to AD pathogenesis:
SYT2 is relevant to PD through:
SYT2 mutations cause familial epilepsy:
Emerging evidence links SYT2 to ALS:
Targeting SYT2 pathways is being explored:
| Strategy | Approach | Status |
|---|---|---|
| Calcium modulators | Modulate presynaptic calcium | Research |
| Gene therapy | Restore SYT2 expression | Preclinical |
| Small molecules | Enhance synaptic function | Discovery |
SYT2 as a synaptic biomarker:
Jackman SL, et al. The Synaptotagmin superfamily. Neuron. 2016. ↩︎ ↩︎ ↩︎