BRS2(KC2) - Methionine & Transsulfuration Substrate Pool
1. Definition
Availability of amino-acid substrates supporting methionine cycling, transsulfuration flux, glutathione synthesis, and related methylation-dependent pathways.
2. Constraint Role
Provides the shared amino-acid substrate pool required for methionine metabolism and downstream sulfur-amino-acid pathways. Supports multiple methylation-related PMs by maintaining substrate availability for methionine regeneration, SAMe production, homocysteine metabolism, transsulfuration activity, and glutathione synthesis.
3. Shared Biological Pool
- Methionine
- Serine
- Glycine
- Cysteine
- Sulfur-containing amino acids
- Amino-acid substrates supporting transsulfuration and glutathione synthesis
4. Biological Importance
The methionine cycle and transsulfuration pathway depend upon a shared pool of amino-acid substrates that support methylation capacity, sulfur metabolism, antioxidant defence, and glutathione production. These substrates contribute to both methyl-group metabolism and downstream protective pathways. Insufficient substrate availability may reduce the efficiency and resilience of multiple interconnected methylation processes.
5. Connected Mechanisms
Functional Mechanisms
- BRS2(FM1) - Methylation Cycle Efficiency
- BRS2(FM2) - Transsulfuration & Redox Coupling
- BRS2(FM3) - Methylation–Membrane Coupling
Primary Mechanisms
- BRS2(PM1) - Folate/B12-Dependent Homocysteine Remethylation
- BRS2(PM3) - SAMe Synthesis
- BRS2(PM4) - Methionine Cycle Flux
- BRS2(PM5) - Transsulfuration Pathway
- BRS2(PM6) - Glutathione Synthesis
- BRS2(PM7) - Phospholipid Methylation
6. Constraint Stressors / Burdens
- Low protein quality or insufficient sulfur-amino-acid intake
- Chronic methionine substrate insufficiency
- Increased glutathione demand
- Increased oxidative burden driving sulfur-amino-acid utilisation
- Restrictive dietary patterns reducing substrate diversity
7. References
- See linked FM and PM pages for cited evidence.