SYNJ1: Synaptojanin 1 Gene
A key regulator of synaptic vesicle endocytosis and phosphoinositide metabolism
Gene Information Card
| Symbol | SYNJ1 |
|---|---|
| Full Name | Synaptojanin 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 21q22.11 |
| NCBI Gene ID | 8867 ncbi.nlm.nih.gov/gene/8867 |
| Ensembl ID | ENSG00000159069 |
| UniProt ID | O43426 |
| OMIM ID | 604297 |
| HGNC ID | 11503 |
| Aliases | KIAA0729, PARK20, INPP5G |
Description
SYNJ1 encodes synaptojanin 1, a phosphoinositide phosphatase that dephosphorylates phosphatidylinositol (4,5)-bisphosphate (PIP2) and phosphatidylinositol (3,4,5)-trisphosphate (PIP3). It is essential for clathrin-mediated endocytosis at synapses, regulating synaptic vesicle recycling. Mutations in SYNJ1 are associated with early-onset Parkinson disease (PARK20) and epileptic encephalopathy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Early-onset Parkinson disease 20 (PARK20) | Loss-of-function mutations impair synaptic vesicle endocytosis, leading to dopamine neuron degeneration | ClinVar, OMIM |
| Epileptic encephalopathy, early infantile, 53 | Homozygous or compound heterozygous mutations disrupt synaptic function | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.5 | High |
| Testis | 4.2 | Medium |
| Adrenal gland | 3.1 | Medium |
| Lung | 1.8 | Low |
| Liver | 0.5 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| SH-SY5Y (neuroblastoma) | 15.3 | Neuronal model |
| HEK293 (embryonic kidney) | 2.1 | Low endogenous expression |
| U-87 MG (glioblastoma) | 8.7 | Moderate expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.773G>A (p.Arg258Gln) | Missense | Rare | Impaired phosphatase activity; associated with PARK20 |
| c.1013C>T (p.Thr338Met) | Missense | Rare | Reduced protein stability; linked to early-onset parkinsonism |
| c.2380G>A (p.Glu794Lys) | Missense | Rare | Disrupts SAC1 domain function; epileptic encephalopathy |
Mutation functional classification
Loss of Function (LOF)
Most pathogenic SYNJ1 mutations reduce phosphatase activity or protein stability, impairing endocytosis.
Gain of Function (GOF)
No evidence of gain-of-function mutations.
Dominant Negative (DN)
Not reported; inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Clathrin-mediated endocytosis (Reactome R-HSA-8856828)
• Phosphoinositide metabolism (Reactome R-HSA-1660499)
• Synaptic vesicle cycle (KEGG hsa04721)
Protein Summary
Synaptojanin 1 is a 160 kDa protein with an N-terminal Sac1-like phosphatase domain and a central 5-phosphatase domain. It localizes to nerve terminals and dephosphorylates PIP2, facilitating clathrin uncoating during synaptic vesicle recycling. The protein interacts with endophilin and dynamin, and its dysfunction leads to accumulation of coated vesicles and neurodegeneration.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SYNJ1 Knockout HEK293 Cell Line | EDJ-KQ1656 | Human | 8867 | Details Get a Quote |
| SYNJ1 Knockout A-549 Cell Line | EDJ-KQ21406 | Human | 8867 | Details Get a Quote |
| SYNJ1 Knockout HCT 116 Cell Line | EDJ-KQ21407 | Human | 8867 | Details Get a Quote |
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