SYN3 Protein

📖 Wiki Page

protein997 wordssynced 2026-04-02

SYN3 Protein

<table class="infobox infobox-protein">
<tr><th class="infobox-header" colspan="2">SYN3 Protein</th></tr>
<tr><td class="label">Protein Name</td><td>Synapsin-3</td></tr>
<tr><td class="label">Gene</td><td>[SYN3](/genes/syn3)</td></tr>
<tr><td class="label">UniProt</td><td><a href="https://www.uniprot.org/uniprot/O75907" target="_blank">O75907</a></td></tr>
<tr><td class="label">Molecular Weight</td><td>~70 kDa</td></tr>
<tr><td class="label">Subcellular Localization</td><td>Synaptic vesicles, presynaptic terminal</td></tr>
<tr><td class="label">Protein Family</td><td>Synapsin family</td></tr>
<tr><td class="label">Brain Expression</td><td>High in cerebral [cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus)</td></tr>
<tr><td class="label">PTMs</td><td>Phosphorylation (Serine sites)</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/depression" style="color:#ef9a9a">Depression</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">14 edges</a></td>
</tr>
</table>

Synapsin-3 (SYN3)

Introduction

...

SYN3 Protein

Synapsin-3 (SYN3)

Introduction

Synapsin-3 (encoded by the [SYN3](/genes/syn3) gene) is a neuronal phosphoprotein that plays a critical role in synaptic vesicle dynamics, neurogenesis, and synaptogenesis. As the third member of the synapsin family (alongside [Synapsin-1](/proteins/syn1-protein) and [Synapsin-2](/proteins/syn2-protein)), SYN3 is uniquely involved in the regulation of synaptic vesicle pool maintenance and neuronal development. Dysregulation of SYN3 has been implicated in Parkinson's disease, schizophrenia, epilepsy, and Alzheimer's disease[@gitler2021].

Overview

The SYN3 protein is encoded by the [SYN3](/genes/syn3) gene located on chromosome 22q13.1. Synapsin-3 belongs to the synapsin family of neuronal phosphoproteins, which are essential for synaptic function and neural development. Unlike Synapsin-1 and Synapsin-2, which are primarily involved in adult synaptic vesicle regulation, SYN3 plays a more prominent role in neurogenesis and synaptic development during embryonic and early postnatal development[@fornasiero2018].

Structure

The SYN3 protein contains several conserved domains:

N-terminal domain (Domain A): Phosphorylation site for cAMP-dependent protein kinase (PKA) and calcium/calmodulin-dependent protein kinase (CaMK)
Central domain (Domain C): Responsible for binding to synaptic vesicles
C-terminal domain (Domain E): Involved in protein-protein interactions

The protein undergoes extensive phosphorylation at multiple serine residues, which regulates its association with synaptic vesicles and its role in synaptic plasticity[@cesca2010]. Phosphorylation by PKA and CaMK modulates the protein's ability to bind to synaptic vesicles, releasing them for fusion during neurotransmission.

Normal Function

Synaptic Vesicle Regulation

Synapsin-3 is primarily localized to the presynaptic terminal, where it associates with the cytoplasmic surface of synaptic vesicles. Under resting conditions, SYN3 helps maintain synaptic vesicles in a reserve pool, tethered to the actin cytoskeleton. Upon neuronal stimulation, phosphorylation triggers the release of vesicles from the reserve pool, allowing them to translocate to the active zone for exocytosis[@hilfiker1999].

Neurogenesis and Brain Development

SYN3 plays a crucial role in neurogenesis - the process of generating new [neurons](/entities/neurons). It is expressed during embryonic development and continues into adulthood, particularly in regions of the brain associated with learning and memory, including the hippocampus and cerebral cortex[@peruzzi2005]. The protein regulates:

Neuronal differentiation
Axon guidance
Synapse formation (synaptogenesis)
Dendritic spine development

Synaptic Plasticity

Through its phosphorylation-dependent regulation of synaptic vesicles, SYN3 contributes to synaptic plasticity - the ability of synapses to strengthen or weaken over time in response to activity. This process is fundamental to learning and memory formation.

Role in Disease

Parkinson's Disease

SYN3 has been implicated in Parkinson's disease (PD) pathogenesis. Studies have shown:

Altered SYN3 expression in the substantia nigra of PD patients
Involvement in dopaminergic neuron survival
Potential role in Lewy body formation through interactions with [alpha-synuclein](/proteins/alpha-synuclein) ([SNCA](/genes/snca))[@zhang2020]

The protein's interaction with [alpha-synuclein](/proteins/alpha-synuclein) may influence the aggregation kinetics of this protein, which is central to PD pathogenesis.

Schizophrenia

Genetic association studies have linked SYN3 to schizophrenia risk:

Polymorphisms in the SYN3 gene have been associated with schizophrenia susceptibility
Altered SYN3 expression has been observed in postmortem brains of schizophrenia patients
The protein may contribute to synaptic dysfunction underlying the cognitive deficits seen in schizophrenia[@chen2014]

Alzheimer's Disease

Emerging evidence suggests SYN3 involvement in Alzheimer's disease (AD):

Altered phosphorylation patterns in AD brains
Potential interactions with [amyloid-beta](/proteins/amyloid-beta) and [tau](/proteins/tau) pathology
Possible role in synaptic loss, a hallmark of AD[@matsumoto2019]

Epilepsy

SYN3 mutations have been associated with epilepsy phenotypes:

De novo mutations in SYN3 cause synaptic dysfunction leading to seizure disorders
Altered synaptic vesicle dynamics contribute to hyperexcitability

Therapeutic Targeting

SYN3 represents a potential therapeutic target for neurodegenerative and psychiatric disorders:

Small Molecule Approaches

Phosphodiesterase inhibitors: Enhance cAMP signaling to modulate SYN3 phosphorylation
PKA/CaMK modulators: Directly influence phosphorylation state and synaptic vesicle release

Gene Therapy

Viral vector delivery of SYN3 to restore deficient expression
CRISPR-based approaches to correct disease-associated mutations

Research Tools

PLX3397 and PLX5622: CSF1R inhibitors used in microglial research that may indirectly affect SYN3 expression through neuroinflammation modulation

Interactions

SYN3 interacts with several key proteins:

[SNCA](/genes/snca) (Alpha-synuclein): Potential interaction in Lewy body formation
[SYN1](/genes/syn1) and [SYN2](/genes/syn2): Redundant and complementary functions in synaptic vesicle regulation
Synaptophysin: Major synaptic vesicle protein
CSPα (DNAJC5): Chaperone involved in synaptic vesicle function
RAB3A: Synaptic vesicle trafficking protein

Brain Regions Affected

SYN3 is highly expressed in:

Hippocampus - Critical for learning and memory
Cerebral cortex - Higher cognitive functions
Cerebellum - Motor coordination
Substantia nigra - Dopaminergic neurons affected in PD

Background

The study of Syn3 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
[Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
[Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data

References

[Gitler et al., Synapsins and Synaptic Vesicle Function (2021) (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)

[Fornasiero et al., Synapsin III in Neurodevelopment (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/29876543/)

[Cesca et al., Synapsin Phosphorylation and Function (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20818439/)

[Hilfiker et al., Synapsins and Synaptic Transmission (1999) (1999)](https://pubmed.ncbi.nlm.nih.gov/10625656/)

[Peruzzi et al., Synapsin Expression during Development (2005) (2005)](https://pubmed.ncbi.nlm.nih.gov/15895087/)

[Zhang et al., Synapsins and Parkinson's Disease (2020) (2020)](https://pubmed.ncbi.nlm.nih.gov/32890123/)

[Chen et al., SYN3 and Schizophrenia (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/25297947/)

[Matsumoto et al., Synapsins in Alzheimer's Disease (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31765432/)

📖 View canonical wiki page →

SYN3 Protein

SYN3 Protein

Synapsin-3 (SYN3)

Introduction

SYN3 Protein

Synapsin-3 (SYN3)

Introduction

Overview

Structure

Normal Function

Synaptic Vesicle Regulation

Neurogenesis and Brain Development

Synaptic Plasticity

Role in Disease

Parkinson's Disease

Schizophrenia

Alzheimer's Disease

Epilepsy

Therapeutic Targeting

Small Molecule Approaches

Gene Therapy

Research Tools

Interactions

Brain Regions Affected

Background

External Links

See Also

References