SMN1 Gene: Survival of Motor Neuron 1
Essential gene for motor neuron survival; mutations cause spinal muscular atrophy (SMA).
Gene Information Card
| Symbol | SMN1 |
|---|---|
| Full Name | Survival of Motor Neuron 1, Telomeric |
| Gene Type | Protein coding |
| Chromosomal Location | 5q13.2 |
| NCBI Gene ID | 6606 ncbi.nlm.nih.gov/gene/6606 |
| Ensembl ID | ENSG00000172062 |
| UniProt ID | Q16637 |
| OMIM ID | 600354 |
| HGNC ID | 11117 |
| Aliases | SMN, SMA, SMA1, SMA2, SMA3, SMA4, BCD541, TDRD16A |
Description
The SMN1 gene encodes the survival motor neuron (SMN) protein, which is critical for the assembly of small nuclear ribonucleoproteins (snRNPs) and pre-mRNA splicing. It is located in a complex region on chromosome 5q13 that contains a nearly identical copy, SMN2. SMN1 is the primary functional gene; mutations or deletions cause spinal muscular atrophy (SMA), a severe neuromuscular disorder. The SMN protein is ubiquitously expressed but its deficiency particularly affects motor neurons, leading to muscle weakness and atrophy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Spinal Muscular Atrophy (SMA) types 1-4 | Loss of SMN1 function due to homozygous deletion or mutation; SMN2 copy number modifies severity. | ClinVar, OMIM |
| SMA with respiratory distress (SMARD) | Rare; mutations in SMN1 can cause atypical forms, though SMARD is usually linked to IGHMBP2. | OMIM |
| Arthrogryposis multiplex congenita (some cases) | Severe SMN1 mutations leading to fetal akinesia. | OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.4 | Medium |
| Spinal Cord | 8.2 | Low |
| Brain | 7.5 | Low |
| Muscle | 5.1 | Low |
| Liver | 4.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 10.5 | Cervical cancer cell line |
| K562 | 8.9 | Leukemia cell line |
| MCF7 | 7.8 | Breast cancer cell line |
| HepG2 | 6.2 | Liver cancer cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.840C>T (in SMN2, not SMN1) | Splice variant | Common in SMA patients (SMN2 exon 7 skipping) | Loss of SMN protein function |
| c.5C>T (p.Ala2Val) | Missense | Rare | Disrupts SMN oligomerization |
| c.399_402delAGAG (p.Glu134fs) | Frameshift | Rare | Truncated protein, loss of function |
| Whole gene deletion | Copy number variant | ~95% of SMA cases | Complete loss of SMN1 |
Mutation functional classification
Loss of Function (LOF)
Most SMN1 mutations are loss-of-function, leading to reduced SMN protein levels and impaired snRNP assembly, causing motor neuron degeneration.
Gain of Function (GOF)
No gain-of-function mutations reported for SMN1.
Dominant Negative (DN)
Some missense mutations may act in a dominant-negative manner, but SMA is typically autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • RNA binding | • protein binding |
| • U snRNP binding | • mRNA splicing |
| • SMN complex | • cytoplasm |
| • nucleus | • gem |
Pathways
• mRNA Splicing - Major Pathway
• SMN Complex Assembly
• snRNP Biogenesis
Protein Summary
The SMN protein (294 amino acids, ~38 kDa) is a multifunctional protein involved in the assembly of spliceosomal snRNPs. It contains a Tudor domain that binds to Sm proteins, a YG-box, and a proline-rich region. SMN forms a complex with Gemin2-8 and other proteins, essential for the cytoplasmic assembly of snRNPs. In motor neurons, SMN also plays roles in axonal transport and mRNA localization. Deficiency leads to selective motor neuron death, though the exact mechanism is still under investigation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SMN1 Knockout HEK293 Cell Line | EDJ-KQ50638 | Human | 6606 | Details Get a Quote |
| SMN1 Knockout HeLa Cell Line | EDJ-KQ54525 | Human | 6606 | Details Get a Quote |
| SMN1 Knockout A-549 Cell Line | EDJ-KQ63009 | Human | 6606 | Details Get a Quote |
| SMN1 Knockout HCT 116 Cell Line | EDJ-KQ71484 | Human | 6606 | Details Get a Quote |
