Genetic code expansion: Bridging synthetic biology precision and cellular complexity to decipher molecular mechanisms...

Despite major advances in biomedical research, dissecting disease-relevant molecular pathways remains challenging due to pathway redundancy, transient protein interactions, and the limited spatiotemporal precision of existing tools. Genetic code expansion (GCE) addresses these limitations by enabling site-specific incorporation of noncanonical amino acids that endow proteins with novel chemical, photophysical, or regulatory properties directly in living systems. This capability provides unique access to dynamic protein interactions, post-translational modifications, and signaling events in cellular environments. Here, we highlight recent advances in GCE that are particularly adapted to studying disease biology in increasingly physiologically relevant contexts, discuss key challenges limiting broader implementation, and outline emerging methodologies that position this technology as a transformative synthetic biology platform for mechanistic dissection of disease processes.