Snitrosylated

Snitrosylated describes proteins or other thiol-containing molecules that have undergone S-nitrosylation, a nitric oxide–dependent post-translational modification in which a nitroso group is added to a cysteine thiol to form an S-nitrosothiol (RS-NO). This modification is reversible and serves as a redox-based signaling mechanism in cells.

Formation occurs via nitrosating species such as nitrosonium (NO+) or dinitrogen trioxide (N2O3), through transnitrosylation from existing S-nitrosothiols (e.g., GSNO), or via metal-catalyzed routes. The result is a modification at cysteine residues that can alter protein activity, interactions, localization, and stability. S-nitrosylation is context-dependent and can either inhibit or enhance function, for example by inhibiting caspases to block apoptosis or by modulating enzymes such as GAPDH or ion channels.

Denitrosylation processes reverse the modification, mediated by enzymes such as thioredoxin family proteins or glutathione-dependent systems; GSNOR (GSNO reductase) regulates cellular S-nitrosothiol pools by metabolizing GSNO.

Detection and measurement rely on biochemical and proteomic approaches, including the biotin-switch method and mass spectrometry, though in vivo interpretation remains challenging due to the labile and transient nature of RS-NO.

Physiological relevance spans cardiovascular signaling, neuronal transmission, and immune responses, while dysregulation is linked to nitrosative stress and various diseases. Snitrosylated proteins thus represent a dynamic component of redox signaling and proteome regulation.