Cys151

Cys151 is a designation used in protein sequence data to refer to the cysteine residue at position 151 in a particular polypeptide. The significance of Cys151 depends on the specific protein and its context. Cysteine residues are notable for their thiol (-SH) side chain, which is reactive and can participate in catalysis, form disulfide bonds with other cysteines, coordinate metal ions, or undergo redox-based post-translational modifications.

In some proteins, a cysteine at position 151 may contribute to catalytic activity if it lies in or near an active site, acting as a nucleophile or redox mediator. In others, Cys151 could help stabilize structure through disulfide bonding or participate in metal coordination. The functional importance of Cys151 is often suggested by its conservation across related proteins; highly conserved cysteines are more likely to be functionally significant. Conversely, mutation of Cys151 (for example, to serine or alanine) is a common experimental approach to probe its role, with effects assessed on activity, stability, folding, or localization.

Cys151 can also be subject to redox-related modifications, such as oxidation to sulfenic, sulfinic, or sulfonic acid forms, or reversible S-nitrosylation, which can regulate protein function. Structural and biochemical studies, including X-ray crystallography, NMR, mutagenesis, and mass spectrometry, are used to determine whether Cys151 participates in disulfide bonds, metal binding, or catalytic mechanisms.

Residue numbering is protein-specific and may vary with isoforms, mature forms, or sequence updates, so the exact role of Cys151 must be interpreted in the proper molecular context.