SUBCELLULAR FRACTIONATION EVIDENCE FOR A PUTATIVE PEROXISOME-MITOCHONDRION ATTACHMENT IN THE LIVER OF NORMAL AND GENETICALLY-OBESE (OB OB AND DB DB) MICE

1. Liver post-nuclear supernatants (PNS) from several mouse strains were fractionated by zonal centrifugation and fractions analysed by marker-enzyme estimations + electron microscopy. 2. Rate-dependent banding of PNS yielded peroxisome-enriched (PER) and mitochondrion-enriched (MER) regions. 3. Density-dependent banding of PER yielded peroxisomes (almost-equal-to 1.22 g/ml) well separated from mitochondria (almost-equal-to 1.8 g/ml). 4. Density-dependent banding of MER yielded peroxisomes that co-distributed with mitochondria and electron microscopy revealed close proximity of the two organelles. 5. Experiments demonstrated that co-distribution was not due to weak binding of proteins or to agglutination of organelles. 6. The results indicate in vivo attachment of some mitochondria and peroxisomes.