Table 2.

Various modifications and interactions regulating thioredoxin activity

Post-translational modification	Amino acid involved	Function
Post-translational modifications that regulate thioredoxin activity
1. Glutathionylation	Cys-73 in eukaryotic cells and cys-60 in plants	Significant reduction in Trx activity
2. Thiol- oxidation of Trx	Cys-32, 39 in redox regulatory domain	Binds to different proteins and regulates their protein functions
3. S-nitrosylation	Cys-69 and Cys-73 outside the regulatory region	Increased activity of thioredoxin and accounting for anti-apoptotic capacity of Trx
Thioredoxin interacting protein that regulates Trx functions
1. TXNIP	Cys-247 of TXNIP interacts with thioredoxin	Inhibit thioredoxin
2. ASK-1	Trx binds to the N-terminal of ASK-1	Reduced thioredoxin binds ASK1 to inhibit downstream signaling
3. PKC	Binds to the catalytic domain of thioredoxin	Thioredoxin inhibits PKC-mediated histone phosphorylation