The multiple nicotinamide nucleotide-binding subunits of bovine heart mitochondrial NADH:ubiquinone oxidoreductase (complex I).
Direct photoaffinity labeling of purified bovine heart NADH:ubiquinone oxidoreductase (complex I) with 32P-labeled NAD(H), NADP(H) and ADP has shown that five polypeptides become labeled, with molecular masses of 51, 42, 39, 30, and 18-20 kDa. The 51 and the 30-kDa polypeptides were labeled with either [32P]NAD(H), [32P]NADP(H) or [beta-32P]ADP. The 42-kDa polypeptide was labeled with [32P]NAD(H) and to a small extent with [beta-32P]ADP. It was not labeled with [32P]NADP(H). The 39-kDa polypeptide was labeled with [32P]NADPH and to a small extent with [beta-32P]ADP. Our previous studies had shown that this subunit also binds NADP, but not NAD(H) [Yamaguchi, M., Belogrudov, G.I. & Hatefi, Y. (1998) J. Biol. Chem. 273, 8094-8098]. The 18-20-kDa polypeptide was labeled only with [32P]NADPH. Among these polypeptides, the 51-kDa subunit is known to contain FMN and a [4Fe-4S] cluster, and is the NAD(P)H-binding subunit of the primary dehydrogenase domain of complex I. The possible roles of the other nucleotide-binding subunits of complex I have been discussed.
Yamaguchi
M
M
Division of Biochemistry, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA.
Belogrudov
G I
GI
Matsuno-Yagi
A
A
Hatefi
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D042967:Electron Transport Complex I; D005420:Flavoproteins / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism*; D008969:Molecular Sequence Data; D009243:NAD / Q000737:chemistry / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D009249:NADP / Q000737:chemistry / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D019920:Photoaffinity Labels / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D005420:Flavoproteins; D010761:Phosphorus Radioisotopes; D019920:Photoaffinity Labels; D009243:NAD; D009249:NADP; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I