Intramitochondrial distribution of three acyl-CoA dehydrogenases in rat liver parenchymal cells revealed by quantitative immunoelectron microscopy.

Abstract

Intramitochondrial distribution of 3 acyl-CoA dehydrogenases in parenchymal cells of rat liver was investigated by means of a post-embedding immunocytochemical technique. Vibratome sections of rat liver fixed with 4% formaldehyde + 1% glutaraldehyde were embedded in Lowicryl K4M at -20.degree. C. Ultrathin sections were incubated with antibodies against short-chain acyl-CoA dehydrogenase (SCAD), medium-chain acyl-CoA dehydrogenase (MCAD) and long-chain acyl-CoA dehydrogenase (LCAD), respectively, followed by a protein A-gold complex. The gold particles representing the antigenic sites for 3 acyl-CoA dehydrogenases were present exclusively in mitochondria. Quantitative analysis of labeling density confirmed that the labeling density for the enzymes were significantly high in the mitochondria. The histogram analyzing the distribution pattern demonstrated that the most of the gold particles were found in zone with a width of .apprx. 12 nm along the innermembrane. Mitochondrial acyl-CoA dehydrogenases are associated with the mitochondrial innermembrane.