Bispecific GTACs antagonize GPCRs by sending them to the lysosome
- GPCR–TfR1 targeting chimeras (GTACs) are bispecific antibodies that pair a receptor binder with a transferrin-receptor binder.
- They drive endocytosis and lysosomal degradation of the GPCR, rather than blocking the orthosteric site.
- Reported for BILF1, RXFP1 and CCR6, covering viral, cancer and immune targets that are hard to drug.
- Signalling, including constitutive activity, was fully shut down, with markedly greater potency than conventional antibody antagonists.
💡 Points
Degrading the receptor sidesteps the usual GPCR headache of finding a clean orthosteric or allosteric small molecule, and it kills constitutive signalling that inverse agonists only partly touch. The catch for my own work: it is an antibody format, so oral exposure and tissue reach are off the table, and TfR1 recruitment brings its own distribution and safety questions. Still, it hands us a genuine alternative mechanism for orphan-like GPCRs where chemistry has stalled.
GPCR antagonism via rewiring of receptor trafficking and degradation ↗