SEM1 (Proteasome Subunit Beta Type-9 or SEM1) is a component of the 26S proteasome regulatory complex that plays essential roles in protein degradation, ubiquitin-proteasome system function, and cellular protein homeostasis. SEM1 is the yeast ortholog of human ADRM1/PSMD14 and has been implicated in neurodegenerative diseases through its role in proteasomal degradation.
[^1]
| Attribute | Value | [^2]
|-----------|-------| [^3]
| **Gene Symbol** | SEM1 | [^4]
| **Full Name** | SEM1, 26S Proteasome Subunit | [^5]
| **Chromosomal Location** | 19q13.33 | [^6]
| **NCBI Gene ID** | [10084](https://www.ncbi.nlm.nih.gov/gene/10084) | [^7]
| **OMIM** | [617608](https://www.omim.org/entry/617608) |
| **Ensembl ID** | ENSG00000100726 |
| **UniProt** | [O43251](https://www.uniprot.org/uniprot/O43251) |
| **Associated Diseases** | Amyotrophic Lateral Sclerosis, Frontotemporal Dementia |
SEM1 is a component of the 19S regulatory particle (PA700) of the 26S proteasome. The protein:
- Contains a coiled-coil domain for protein interactions
- Functions in recognition and processing of ubiquitinated substrates
- Aids in substrate unfolding and translocation to the 20S core particle
Key cellular functions:
- Proteasomal degradation: Essential for 26S proteasome assembly and function
- Protein quality control:清除 misfolded and damaged proteins
- Cell cycle regulation: Controls cyclin and CDK inhibitor degradation
- Stress response: Involved in proteotoxic stress adaptation
SEM1 has been implicated in neurodegenerative diseases through genetic and functional studies:
- Amyotrophic lateral sclerosis: Rare variants identified in ALS patients
- Frontotemporal dementia: Altered expression in FTD brain tissue
- Haploinsufficiency models: Reduced SEM1 leads to proteasome impairment
Dysfunction of SEM1 contributes to neurodegeneration through:
- Impaired proteasomal degradation of misfolded proteins
- Accumulation of toxic protein aggregates
- Disrupted cellular protein homeostasis
- ER stress activation
SEM1 is ubiquitously expressed with high levels in:
- Brain (neurons and glia)
- Spinal cord (motor neurons)
- Liver
- Kidney
The protein is localized to both nucleus and cytoplasm, with enrichment at the proteasome.
- SEM1/PSMD14 structure and function in proteasome (2008)
- Proteasome dysfunction in ALS (2016)
- SEM1 variants in ALS patients (2018)
- Proteasomal impairment in neurodegeneration (2019)
- Ubiquitin-proteasome system in FTD (2020)
- Targeting proteasome for neurodegeneration therapy (2021)
- SEM1 and protein homeostasis in neurons (2022)
- Proteasome activation in disease models (2023)