Enhancement of Coproporphyrinogen III Transport into Isolated Transformed Leukocyte Mitochondria by ATP

It has been proposed that in normal animal cells, biosynthesis of the heme precursor protoporphyrin IX (Proto) requires cooperation between the mitochondria and cytoplasm [S. Granick (1967)inBiochemistry of the Chloroplast (Goodwin, T. W., Ed.), pp. 373–410, Academic Press, NY]. In this work, the conversion of ALA to Coprogen in the cytoplasm of MLA 144 cells (a retrovirally transformed gibbon ape leukemic T cell line) is demonstrated. This in turn indicates that the intracellular localization of Coprogen biosynthesis in transformed animal cells is similar to that proposed for normal animal cells. It is also shown that in MLA 144 cells, after ALA conversion to Coprogen in the cytoplasm, Coprogen is transported into the mitochondria via an ATP-dependent process. The possible involvement of the mitochondrial peripheral-type benzodiazepine receptor (M-PBR) in Coprogen transport into mitochondria is discussed.