A) myoglobin proteinB) Fo-F1 ATPaseC) uncoupling proteinD) transducin proteinE) none of theseAns: uncoupling protein
- Uncoupling occurs naturally in brown adipose tissue. This tissue is rich in mitochondria, the inner mitochondrial membranes of which contain a protein called uncoupling protein (Thermogenin).
- Thermogenin allows H+ ions to flow back into mitochondria without having to enter via the ATP synthase and so uncouples electron transport and oxidative phosphorylation, generating heat.
- The importance of this natural phenomenon is that brown adipose tissue is found in sensitive body areas of some newborn animals (including humans) where the heat production provides protection from cold conditions.
- Thermogenesis by brown adipose tissue plays a role in maintaining body temperature in hibernating animals (Polar bears).
- It is a globular protein made up of a single polypeptide chain of 153 amino acid residues.
- It was the first to protein have its three- dimensional structure solved by X-ray crystallography.
- ATP synthase: Large enzyme complex of the inner mitochondrial catalyzes the formation of ATP from ADP and Pi, accompanied by the flow of protons.
- ATP synthase (complex-V) has two functional domains: Fo & F1
- F1, a peripheral membrane protein, and Fo (o denotes oligomycin sensitive), which is integral to the membrane.
- F1, the first factor recognized as essential for oxidative phosphorylation.
- Transducin is a 3-subunit guanine nucleotide-binding protein (G protein) which stimulates the coupling of rhodopsin and cGMP-phoshodiesterase during visual impulses.