| Property | Value |
|---|---|
| Protein Name | Glutathione S-transferase Mu 1 |
| Gene | GSTM1 |
| UniProt ID | P09488 |
| PDB ID | 1XWK, 3JUK, 4P3Q, 4LJQ |
| Molecular Weight | ~26 kDa |
| Subcellular Localization | Cytoplasm (predominant), mitochondria |
| Protein Family | Mu class glutathione S-transferase family |
| Expression | Ubiquitous, high in liver, brain |
Glutathione S-transferase Mu 1 (GSTM1) is a 218-amino acid cytosolic detoxification enzyme that catalyzes the conjugation of reduced glutathione (GSH) to a wide variety of electrophilic compounds. As a member of the Mu class of GSTs, GSTM1 plays a critical role in cellular detoxification of both endogenous reactive metabolites and exogenous xenobiotics, including environmental toxins, pesticides, and drugs[1].
The GSTM1 gene is notable for its common null polymorphism (GSTM1*0), present in approximately 35-50% of populations of European and African descent, which results in complete loss of GSTM1 enzyme activity. This genetic variant has been extensively studied as a risk factor for Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis, where gene-environment interactions between GSTM1 deficiency and toxin exposure significantly increase disease risk[2].
The GSTM1 protein exhibits the characteristic structure of cytosolic GSTs with specialized features for its detoxification function[3]:
N-Terminal Domain (G-site, aa 1-80): Contains the glutathione (GSH) binding site that recognizes and binds the tripeptide GSH with high affinity. Key residues include Tyr6 and Gln67 that form hydrogen bonds with GSH.
C-Terminal Domain (H-site, aa 90-218): The hydrophobic substrate binding site that accommodates a wide range of electrophilic substrates. This domain determines the substrate specificity of GSTM1.
Active Site Cysteine (Cys47): The catalytic cysteine that forms a reversible bond with electrophilic substrates, facilitating the transfer to GSH.
Conserved Mu Class Motifs: GSTM1 contains characteristic sequence motifs that define the Mu class:
Dimeric Structure: GSTM1 functions as a homodimer. Dimerization is required for enzymatic activity, as each monomer contributes to the formation of the active site at the dimer interface.
GSTM1 has broad substrate specificity, conjugating:
| Category | Substrates |
|---|---|
| Environmental | Pesticides, herbicides, industrial chemicals |
| Endogenous | Lipid peroxidation products (4-HNE, MDA) |
| Drugs | Certain chemotherapeutic agents |
| Neurotoxins | MPTP, 6-OHDA, paraquat metabolites |
| Variant | Effect | Frequency |
|---|---|---|
| GSTM1*0 (deletion) | Complete loss of activity | 35-50% Caucasian |
| GSTM1*2 | Normal activity | Common |
| GSTM1*3 | Variable | Rare |
The null genotype results from a 50 kb deletion spanning the entire GSTM1 gene.
GSTM1 performs essential detoxification and neuroprotective functions in neurons and glia:
GSTM1 deficiency is one of the most well-established genetic risk factors for PD[4][5]:
Increased Oxidative Stress
Dopaminergic Neuron Vulnerability
Environmental Toxin Susceptibility
The gene-environment interaction is critical:
Disease Modifiers
Meta-Analysis Evidence
Multiple studies have confirmed the association:
GSTM1 involvement in AD:
Oxidative Damage
Amyloid Toxicity
Interaction with APOE
Evidence Summary
GSTM1 in motor neuron disease:
| Approach | Status | Notes |
|---|---|---|
| Glutathione supplementation | Phase 2 | Bypass GSTM1 deficiency |
| NAC (N-acetylcysteine) | Phase 1-2 | GSH precursor |
| Sulforaphane | Phase 1 | Nrf2 activator |
| Gene therapy | Preclinical | Not practical |
Bypass Strategies
Expression Enhancement
Substrate Reduction
GSTM1 is regulated by Nrf2-ARE signaling:
Standaert & Holloway, GSTM1 in Parkinson's disease (2018) — Comprehensive review of GSTM1-PD association
Zhao et al., GSTM1 and neurodegeneration (2019) — Meta-analysis of GSTM1 in neurodegeneration
Landi et al., GSTM1 null genotype in PD (2000) — Original landmark study
Hayes & Strange, GSTM1 function (1995) — Comprehensive review of GST biology
Mannervik et al., GSTM1 structure (1985) — Early structural studies
Winter et al., GSTM1 in PD (2019) — Recent evidence
Chen et al., GSTM1 and AD (2017) — AD evidence
Singh et al., GSTM1 neuroprotection (2008) — Mechanism studies
Depeintz et al., GSTM1 detox (2019) — Substrate specificity
Jana & Samanta, GSTM1 oxidative stress (2018) — Oxidative stress role
Patel et al., GSTM1 in PD models (2019) — Model evidence
Wahle et al., GSTM1 and tau (2020) — Tau pathology
Shah et al., GSTM1 gene-environment (2017) — Interaction studies
Menzon et al., GSTM1 variants (2018) — Variant analysis
Johnson et al., GSTM1 clinical (2019) — Clinical studies
Tang et al., GSTM1 in AD (2016) — AD-specific evidence
Federico et al., Antioxidants and GSTM1 (2020) — Therapeutic implications
Ketterer, GSTM1 cancer research (1988) — Historical perspective
Watson et al., GSTM1 null in population (2019) — Population genetics
Caccamo et al., GSTM1 and aging (2020) — Age-related changes