Quantitative autoradiography of dihydrorotenone binding to complex I of the electron transport chain.
Defective complex I activity has been linked to Parkinson's disease and Huntington's disease, but little is known of the regional distribution of this enzyme in the brain. We have developed a quantitative autoradiographic assay using [3H]dihydrorotenone ([3H]DHR) to label and localize complex I in brain tissue sections. Binding was specific and saturable and in the cerebellar molecular layer had a KD of 11.5 +/- 1.3 nM and a Bmax of 11.0 +/- 0.4 nCi/mg of tissue. Unlabeled rotenone and 1-methyl-4-phenylpyridinium ion competed effectively for DHR binding sites. Binding was markedly enhanced by 100 microM NADH. The distribution of complex I in brain, as revealed by DHR autoradiography, is unique but somewhat similar to that of cytochrome oxidase (complex IV). This assay may provide new insight into the roles of complex I in brain function and neurodegeneration.
Greenamyre
J T
JT
Department of Neurology, University of Rochester Medical Center, New York 14642.
Higgins
D S
DS
Eller
R V
RV
D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000201:enzymology / Q000378:metabolism; D004579:Electron Transport; D008297:Male; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012402:Rotenone / Q000378:metabolism*; D014316:Tritium
D012402:Rotenone; D014316:Tritium; D016660:NAD(P)H Dehydrogenase (Quinone)