Figure 1.

Intracellular metabolism of 5-ALA. The synthesis steps of heme metabolism are labelled by blue arrows (↑). Red indicators (T) point to enzymes and substances that inhibit particular steps of metabolism, whereas green indicators (Ψ) highlight factors that promote them. PEPT 1/2—peptide transporter 1/2, ALAS—ALA synthase, ALAD—ALA dehydratase, PBGD—porphobilinogen deaminase, UROS—uroporphyrinogen III synthase, UROD—uroporphyrinogen III decarboxylase, ABCB6—ATP-binding cassette transporter B6, CPOX—coproporphyrinogen III oxidase, FECH—ferrochelatase, ABCG 2—ATP-binding cassette subfamily G 2 Protein, DFO—deferoxamine mesylate, FBS—fetal bovine serum, SnPP—tin protoporphyrin IX, FTC—fumitremorgin C, 5-ALA (endo)—endogenous 5-ALA, 5-ALA (exo)—exogenous 5-ALA.