title: Uptake of protoporphyrin IX by isolated rat liver mitochondria.
abstract: Rat liver mitochondria accumulate protoporphyrin IX from the suspending medium into the inner membrane in parallel with the magnitude of the transmembrane K+ gradient (K+in/K+out). Only protoporphyrin IX taken up in parallel with the transmembrane K+ gradient is available for haem synthesis. Coproporphyrins (isomers I and III) are not taken up by the mitochondria. The results support the suggestion by Elder & Evans [(1978) Biochem. J. 172, 345-347] that the prophyrin to be taken up by the inner mitochondrial membrane belongs to the protoporphyrin(ogen) IX series. Protoporphyrin IX at concentrations above 15 nmol/mg of protein has detrimental effects on the structural and functional integrity of the mitochondria. The relevance of these effects to the hepatic lesion in erythropoietic protoporphyria is discussed.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D006418:Heme / Q000096:biosynthesis; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011524:Protoporphyrins / Q000378:metabolism*; D051381:Rats; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D011166:Porphyrins; D011524:Protoporphyrins; D014634:Valinomycin; D006418:Heme; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D011188:Potassium