molecular glue degrader

A molecular glue degrader is a small molecule that destroys a disease protein by sticking it to the cell's protein-disposal machinery. Like the larger two-headed degraders, it ends with the target being shredded — but instead of having one arm for the target and one for the disposal enzyme, a molecular glue is a single compact molecule that simply makes two proteins suddenly want to hold hands.

The mechanism is a piece of induced matchmaking. The glue tucks into the surface of an E3 ubiquitin ligase, the cell's labeling enzyme, and subtly reshapes it so that it now recognizes a target protein it would normally ignore. The ligase then tags that newly invited target with ubiquitin, marking it for the proteasome to chew up. Strikingly, the target itself may have no real pocket for a drug; the glue creates the interaction surface that drags it to its doom.

The appeal is huge: molecular glues are small, drug-like, often orally available, and can take down proteins long deemed undruggable. The difficulty is that they are hard to design on purpose — many were found by luck — because predicting which small molecule will glue which two proteins together remains a frontier challenge.