GlyXSerXGly

GlyXSerXGly is a short amino acid motif used in protein sequence analysis. It represents a five-residue sequence in which the first and fifth residues are glycine (G), the third is serine (S), and the second and fourth residues are unspecified and denoted by X. In this convention, X stands for any amino acid, allowing the motif to match a range of sequences such as G-A-S-K-G or G-L-S-E-G.

In bioinformatics, GlyXSerXGly is used to search protein databases for occurrences of this pattern, often as part of motif scanning, pattern matching, or motif logos. It can be expressed as a regular expression or as a PROSITE-like pattern. Because X is unspecified, short motifs like this can occur frequently by chance, so biological interpretation usually requires comparison with broader sequence context and conservation across related proteins.

Functional implications of such a motif are context-dependent. The presence of glycine at the ends can contribute to local flexibility, and serine at the center can participate in hydrogen bonding or serve as a potential phosphorylation site depending on the structural and cellular context. However, without supporting structural or experimental data, the motif alone does not determine a specific function.

See also: motifs, PROSITE, sequence logos, regular expressions.