The G4S Linker (polyglycine-serine linker) is a flexible polypeptide linker composed of repeating glycine (Gly) and serine (Ser) residues. Its core structural unit is a pentapeptide sequence Gly-Gly-Gly-Gly-Ser (abbreviated as G4S), which polymerizes into multimeric forms such as the 15-mer (G4S)3 (three repeats) or 20-mer (G4S)4 (four repeats). This sequence design confers high flexibility and unstructured properties, effectively minimizing steric hindrance between connected protein domains.The evolutionary conservation and broad applicability of the G4S Linker have established it as a critical target in antibody engineering and therapeutic development.
