Subunit arrangement in beef heart complex III
Beef heart mitochondrial complex III was separated into 12 polypeptide bands representing 11 different subunits by using the electrophoresis conditions described previously. Eight of the 12 polypeptide bands were identified from their NH/sub 2/-terminal sequences as obtained by electroblotting directly from the NaDodSO/sub 4/-polyacrylamide gel onto a solid support. The topology of the subunits in complex III was explored by three different approaches. (1) Protease digestion experiments of submitochrondial particles in the presence and absence of detergent showed that subunits II and VI are on the M side of the inner membrane and subunits V and XI on the C side. (2) Labeling experiments with the membrane-intercalated probes (/sup 125/I)TID and arylazidoPE indicated that cytochrome b is the predominant bilayer embedded subunit of complex III, while the non-heme iron protein appears to be peripherally located. (3) Cross-linking studies with carbodiimides and homobifunctional cleavable reagents demonstrated that near-neighbor pairs include subunits I+II, II+VI, III+VI, IV+V, V+X, and V+VII. The cytochrome c binding site was found to include subunits IV, VII, and X. The combined data are used to provide an updated model of the topology of beef heart complex III.
- Research Organization:
- Univ. of Oregon, Eugene (USA)
- OSTI ID:
- 6326467
- Journal Information:
- Biochemistry; (United States), Vol. 27:18
- Country of Publication:
- United States
- Language:
- English
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OXIDOREDUCTASES
MOLECULAR STRUCTURE
PHOTOCHEMISTRY
CATTLE
CROSS-LINKING
ELECTROPHORESIS
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IODINE 125
MEMBRANE TRANSPORT
MITOCHONDRIA
NEAR ULTRAVIOLET RADIATION
PEPTIDE HYDROLASES
POLYPEPTIDES
TRITIUM COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELECTROMAGNETIC RADIATION
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
HYDROLASES
INTERMEDIATE MASS NUCLEI
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ISOTOPES
LABELLED COMPOUNDS
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
PEPTIDES
POLYMERIZATION
PROTEINS
RADIATIONS
RADIOISOTOPES
RUMINANTS
ULTRAVIOLET RADIATION
VERTEBRATES
550201* - Biochemistry- Tracer Techniques