HIF-1: the knowns and unknowns of hypoxia sensing

Hypoxia-inducible factor-1 (HIF-1) is a transcriptional activator that functions as a master regulator of cellular and systemic oxygen homeostasis. It consists of two constitutively produced subunits: HIF-1 and HIF-1. Under normoxic conditions HIF-1 undergoes hydroxylation at specific prolyl residues which leads to an immediate ubiquitination and subsequent proteasomal degradation of the subunit. Addi