Journal of Lipid Research, Vol 29, 613-628, Copyright © 1988 by Lipid Research, Inc.
Demonstration of cytochrome reductases in rat liver peroxisomes: biochemical and immunochemical analyses
C Gutierrez, R Okita and S Krisans
Department of Biology, San Diego State University, CA 92182.
In this study we utilized the analytical cell fractionation approach in
combination with immunoblotting techniques and immunoelectron microscopy to
test for the presence of NADPH cytochrome P-450 reductase and NADH
cytochrome c (b5) reductase in rat liver peroxisomes. Highly purified
peroxisomes from clofibrate-treated rats exhibited both NADPH cytochrome
P-450 reductase activity and NADH cytochrome c reductase activity (using
cytochrome c as an electron acceptor). These activities were inhibited by
the respective reductase antibodies made against the endoplasmic reticulum
(ER) enzymes. Immunoblot data in combination with immunoelectron microscopy
indicated that the peroxisomal NADPH cytochrome P-450 reductase is
localized in the matrix of the organelle and has a subunit of molecular
weight similar to that of the ER enzyme, whereas the NADH cytochrome c (b5)
reductase is localized in the membranes of the peroxisomes. Again, the
subunit molecular weight was similar to that of the ER enzyme. The presence
of these reductases in peroxisomes further supports the role of this
organelle in bile acid synthesis and cholesterol metabolism.