Protoporphyrinogen IX is a key intermediate in the biosynthesis of heme, an essential component of hemoglobin and various enzymes. It is produced from porphobilinogen through a series of enzymatic reactions in the mitochondria of cells. This compound is then converted into protoporphyrin IX by the enzyme protoporphyrinogen oxidase. Protoporphyrin IX subsequently combines with iron to form heme, which plays a crucial role in oxygen transport and cellular respiration in living organisms.