G140S

G140S is a protein sequence variant designation used in genetics and molecular biology to denote a missense mutation in which glycine (G) at residue 140 is replaced by serine (S). The notation is protein-centric; it can refer to any gene or protein where the residue 140 is glycine in the reference sequence. Because residue numbering is protein-specific, G140S must be interpreted with the appropriate sequence context.

The functional impact of a G140S substitution is highly context-dependent. Glycine is the smallest amino acid and contributes to conformational flexibility, particularly in tight turns or flexible loops. Replacing it with serine introduces a polar side chain with a hydroxyl group, which can alter local structure, hydrogen bonding networks, or post-translational modification patterns. Depending on the location, G140S can be benign or may affect stability, folding, catalytic activity, or interactions with other molecules.

In research and clinical settings, G140S variants are identified through DNA sequencing or proteomic analyses. Predictive tools (such as structural modeling or in silico scoring) may estimate potential effects, but experimental validation is often needed. Clinical significance, when applicable, is categorized according to established guidelines (for example, pathogenic, likely pathogenic, or variant of uncertain significance) based on segregation data, functional assays, and population frequency.

Because residue numbering differs among proteins, any claim about G140S should specify the protein or gene context.