Ofd1 is a prolyl 4-hydroxylase-like 2-oxoglutarate-Fe(II) dioxygenase that accelerates the degradation of Sre1N in the presence of oxygen. The domain is conserved from yeasts to humans. Yeast Sre1 is the orthologue of mammalian sterol regulatory element binding protein (SREBP), and it responds to changes in oxygen-dependent sterol synthesis as an indirect measure of oxygen availability. However, unlike the prolyl 4-hydroxylases that regulate mammalian hypoxia-inducible factor, Ofd1 uses multiple domains to regulate Sre1N degradation by oxygen; the Ofd1 N-terminal dioxygenase domain is required for oxygen sensing and this Ofd1 C-terminal domain accelerates Sre1N degradation in yeasts [1].

1: Oxygen-regulated degradation of fission yeast SREBP by Ofd1, a prolyl hydroxylase family member. Hughes BT, Espenshade PJ; EMBO J. 2008; [Epub ahead of print] PMID:18418381