Consequences of IkappaB alpha hydroxylation by the factor inhibiting HIF (FIH).

The factor inhibiting HIF-1 (FIH-1) hydroxylates many ankyrin repeat-containing proteins including IκBα. It is widely speculated that hydroxylation of IκBα has functional consequences, but the effects of hydroxylation have not been demonstrated. We prepared hydroxylated IκBα and compared it to the unhydroxylated protein.