G4S Linker is a commonly used flexible amino
acid linker that plays a significant role in antibody expression and design.
The sequence of this linker is （Gly-Gly-Gly-Gly-Ser）n, where "n"
represents the number of repetitions. By altering the value of "n,"
the length of the GS amino acid chain can be optimized to achieve appropriate
separation of antibody or protein domain functions or to maintain necessary
inter-domain interactions. G4S Linker is typically used in single-chain
variable fragments （scFv） and chimeric antigen receptors （CARs） to connect the
variable heavy （VH） and variable light （VL） domains for the recognition of
target antigens. The length of this linker is crucial for controlling the
stability of scFv and the non-covalent association between the VH and VL
domains. In CAR structures, the G4S Linker is located in the extracellular
domain of the scFv, helping to maintain the structure and function of the CAR.
Additionally, G4S Linker is used to detect CAR cells designed with G4S Linker,
which offers high specificity and sensitivity.