Subcellular and submitochondrial localization of inorganic pyrophosphatase in the mammalian heart and liver
Kostenko, E.B.; Smirnova, I.N.; Baĭkov, A.A.; Avaeva, S.M.
Biokhimiia 48(5): 707-713
1983
ISSN/ISBN: 0320-9725 PMID: 6135453 Document Number: 211707
The rat heart and liver homogenates contain 3 forms of inorganic pyrophosphatase designated as I, II and III in accordance with a decrease of their electrophoretic mobility. Separation of the homogenates by stepped density gradient differential centrifugation demonstrated that forms I and II are localized in the hyaloplasm, while form III --in the mitochondria. Liver mitochondria contain in addition some amount of pyrophosphatase II. The hyaloplasm and mitochondria of bovine heart contain 2 enzyme forms, whose mobilities are identical to those of forms I and II. Upon destruction of rat mitochondria by detergent (digitonin, Lubrol WX) treatment, sonication or osmotic shock followed by a freezing-thawing precedure pyrophosphatase II remains bound to the inner membrane fragments. The experimental data provide direct evidence for the existence of a specific membrane pyrophosphatase in the mitochondria.