G154G155

G154G155 is a sequence-annotation label encountered in protein sequence data and related literature. It most commonly refers to a pair of glycine residues at positions 154 and 155 in a protein sequence, noted in sequence alignments, structural reports, or commentary on specific regions of a protein.

In one-letter amino acid notation, G stands for glycine. When used to describe a motif, G154G155 can indicate that the residues at positions 154 and 155 are glycine, or that a glycine-glycine motif is present in that segment of the protein. The notation is typically specific to the particular protein sequence and numbering scheme being discussed.

Usage and interpretation depend on context. Researchers may examine the functional role of residues 154 and 155, such as their influence on local flexibility, backbone angles, or interactions within an active site or binding loop. Mutational analyses are commonly described with substitutions at these positions (for example, G154A or G155V) to assess effects on structure or activity. However, the label G154G155 by itself does not convey functional information without accompanying context such as the protein identity and the sequence version used.

Ambiguity and standards: residue numbering can vary between species, isoforms, or different structural models, so the precise meaning of G154G155 is dataset-dependent. In formal descriptions, it is standard to accompany residue numbers with the protein name, database accession, or sequence reference to ensure clarity and reproducibility.