HMOX2 cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently transferred to bilirubin by biliverdin reductase. Under physiological conditions, the activity of HMOX2 is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed. HMOX2 participates in the production of carbon monoxide in the brain where it operates as a neurotransmitter. HMOX2 is an essential enzyme in heme catabolism and is involved in cellular response to oxidative stress.