Human complex I defects can be resolved by monoclonal antibody analysis into distinct subunit assembly patterns.
Complex I defects are one of the most frequent causes of mitochondrial respiratory chain disorders. Therefore, it is important to find new approaches for detecting and characterizing Complex I deficiencies. In this paper, we introduce a new set of monoclonal antibodies that react with 39-, 30-, 20-, 18-, 15-, and 8-kDa subunits of Complex I. These antibodies are shown to aid in diagnosis of Complex I deficiencies and add understanding to the genotype-phenotype relationships of different mutations. A total of 11 different patients were examined. Four patients had undefined Complex I defects, whereas the other patients had defects in NDUFV1, NDUFS2 (two patients), NDUFS4 (two patients), NDUFS7, and NDUFS8. We show here that Western blotting with these antibodies, particularly when used in conjunction with sucrose gradient studies and enzymatic activity measurements, helps distinguish catalytic versus assembly defects and further distinguishes between mutations in different subunits. Furthermore, different mutations in the same gene are shown to give very similar subunit profiles, and we show that one of the patients is a good candidate for having a defect in a Complex I assembly factor.
Triepels
R H
RH
Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, University Hospital Nijmegen St. Radboud, 6500 HB Nijmegen, the Netherlands.
Hanson
B J
BJ
van den Heuvel
L P
LP
Sundell
L
L
Marusich
M F
MF
Smeitink
J A
JA
Capaldi
R A
RA
D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D017931:DNA Primers; D042967:Electron Transport Complex I; D006801:Humans; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics* / Q000276:immunology
D017931:DNA Primers; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I