For example, the main subunits of NADPH oxidase in mammalian phagocytes, vascular plants, diatoms, and the red macroalgae
Porphyra yezoensis and Chondrus crispus are structurally related (Keller et al., 1998; Torres and Dangl, 2005; Herve et al., 2006), which confirms that this protein is evolutionary ancient.