Fig. 2.

Recombinant p105 and IκBα promote decarboxylation of 2-OG in assays of FIH activity. 2-OG decarboxylation is measured by ¹⁴CO₂ formation. (A) Reactions containing the indicated GST-tagged proteins: HIF-1α 775–826 (HIF-1α C-terminal activation domain); p105 ARD 537–809 (p105 ARD); p105 ARD Asn-678 mutant (p105 ARD(N678A)). Wild type (p105 ARD) but not the N678A mutant promoted 2-OG decarboxylation. Higher background was observed with p105 ARD(N678A) because of less pure preparation of protein. (B) Experiments comparing p105 ARD with full-length IκBα and IκBβ proteins. IκBα, but not IκBβ, promotes 2-OG decarboxylation.