druggability
Druggability is a judgment about whether a target protein has a good place for a drug-like molecule to grab onto. Even if a target clearly causes disease, a drug can only work if it can bind the protein tightly, and that usually requires a pocket of the right size and shape. Druggability asks: is there a handle here that a small molecule can hold?
A highly druggable target tends to have a deep, enclosed pocket with a mix of greasy and polar surfaces, letting a small molecule nestle in and form many favorable contacts. Targets with only shallow, flat, or featureless surfaces are harder, sometimes called undruggable, because there is little for a molecule to grip. Computational tools and experiments try to estimate druggability early, before chemistry begins.
Druggability is not a fixed verdict but depends on the kind of molecule considered. A protein that resists conventional small molecules may yield to a peptide, a covalent binder, or a degrader that only needs to touch the surface briefly. The honest caveat is that druggability predictions are imperfect, and some targets long deemed undruggable have eventually been cracked by new chemical strategies.
The protein KRAS was considered undruggable for decades because its surface lacked a good pocket, until chemists exploited a mutant cysteine to anchor covalent inhibitors.
Druggability can change as new chemical strategies create new ways to bind.
Druggability concerns whether a target can be bound; target validation concerns whether binding it would help. Both must hold for a good drug program.