Egl nine homolog 1 (EGLN1)

Cellular oxygen sensor that catalyzes, under normoxic conditions, the post-translational formation of 4-hydroxyproline in hypoxia-inducible factor (HIF) alpha proteins. Hydroxylates a particular proline found in each of the oxygen-dependent degradation (ODD) domains (N-terminal, NODD, and C-terminal, CODD) of HIF1A.

Also hydroxylates HIF2A. Has a preference for the CODD website for the two HIF1A and HIF1B.