Pathway · 3 proteins
Thiol redox control
Thioredoxin and its reductase support cellular thiol chemistry.
How it works
- Thioredoxin-family proteins and thioredoxin-disulfide reductase provide a candidate thiol-reduction network. A glutaredoxin-family entry and thiol-peroxidase-related components describe additional, partly overlapping functions.
- In a representative thioredoxin cycle, reductase supplies electrons to oxidized thioredoxin, and reduced thioredoxin can reduce compatible target disulfides or support a peroxidase.
- Reduction of one target is coupled to oxidation elsewhere and requires a renewed electron supply. Different family members need not share the same clients or form one linear chain.
Grouped by the atlas’s curated pathway map. The table order is not a proven reaction order.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Thioredoxin | — | — | — | 139 | System only |
| Thioredoxin reductase | 1.8.1.9 | [thioredoxin]-dithiol + NADP(+) = [thioredoxin]-disulfide + NADPH + H(+) | — | 323 | Step named |
| Uncharacterized protein aq_668 | — | — | — | 112 | Step named |
Origins
How could a cell keep its proteins' sulfur groups in the right state before thioredoxin existed?
Naturalistic proposal
None of the books searched discusses the origin of thiol redox control.
Design analysis
Proteins inside the cell must keep their cysteines reduced, while some outside need sulfur bridges to hold their shape. Thioredoxin and its reductase, recharged by NADPH, keep the inside reduced, so this system depends on the cell's energy and cofactor supply.
The wider question for this part of the cell: origins for holding the internal balance.
Sources
- Atlas pathway grouping from the VF5 reference-genome system map (Deckert et al. 1998; Braakman & Smith 2014)
Other pathways in this group: Not yet placed in a pathway