8.A.252. The Heme Oxidase (HO) Family HO1 catalyzes the oxidative cleavage of heme at the alpha-methene bridge carbon, released as carbon monoxide (CO), to generate biliverdin IXalpha, while releasing the central heme iron chelate as ferrous iron (Hwang et al. 2009). It affords protection against programmed cell death, and this cytoprotective effect relies on its ability to catabolize free heme and prevent it from sensitizing cells to undergo apoptosis (Gozzelino et al. 2010).
References:
Gozzelino, R., V. Jeney, and M.P. Soares. (2010). Mechanisms of cell protection by heme oxygenase-1. Annu Rev Pharmacol Toxicol 50: 323-354.
Hwang, H.W., J.R. Lee, K.Y. Chou, C.S. Suen, M.J. Hwang, C. Chen, R.C. Shieh, and L.Y. Chau. (2009). Oligomerization is crucial for the stability and function of heme oxygenase-1 in the endoplasmic reticulum. J. Biol. Chem. 284: 22672-22679.
Niu, X., M. Wang, M. Wang, X. Liu, Y. Zhang, P. Zheng, S. Zhang, T. Liu, Z. Cao, and C. Zhang. (2025). Dracorhodin perochlorate sensitizes colorectal cancer to ferroptosis by activating HMOX1 and inhibiting the SLC7A11/GPX4 axis. Int Immunopharmacol 158: 114827.
Examples:
TC#	Name	Organismal Type	Example
8.A.252.1.1	*Heme oxidase 1 of 288 aas and one C-terminal TMS. Dracorhodin perochlorate sensitizes colorectal cancer to ferroptosis by activating HMOX1 and inhibiting the SLC7A11/GPX4 axis (Niu et al.* 2025).**		HO1 of Homo sapiens

8.A.252.1.2	heme oxygenase (biliverdin-producing), HMOX1, of 296 aas with one C-terminal TMS.		*HMOX1 of Zapornia atra* (Henderson crake)**