G91R

G91R is a missense mutation designation used in genetics and protein science to indicate that glycine (G) at residue 91 in a protein is replaced by arginine (R). This notation is applied to various genes and proteins, so G91R does not refer to a single universal variant but to a specific substitution within a particular protein sequence.

The biochemical consequence of G91R depends on the protein context. Glycine is the smallest amino acid and often contributes to flexibility or tight packing. Replacing it with arginine introduces a larger, positively charged side chain that can disrupt local structure, alter stability, or affect interactions with substrates, cofactors, or other proteins. If residue 91 lies in a catalytic site, binding interface, or a structurally critical region, the effect is more likely to be functionally significant; in other regions, the substitution might be tolerated.

In clinical and research settings, the pathogenicity of a G91R variant is assessed gene by gene. Databases such as ClinVar or locus-specific resources may record observed G91R substitutions and any associated phenotypes. Interpretation often relies on evolutionary conservation, structural data, functional assays, and familial segregation analyses.

Because the G91R designation can arise in diverse proteins, there is no universal effect associated with the mutation. Each instance requires consideration of the specific protein, its structure, function, and role in cellular pathways to determine potential clinical or biological significance. Researchers use computational predictions alongside experimental studies to evaluate its impact.