NADH dehydrogenase biquinone1 beta subcomplex subunit 8, mitochondrial is an enzyme that in humans is encoded by the ''NDUFB8'' gene. NADH dehydrogenase (ubiquinone) 1 beta subcomplex subunit 8 is an accessory subunit of the

NADH dehydrogenase (ubiquinone) Respiratory complex I, (also known as NADH:ubiquinone oxidoreductase, Type I NADH dehydrogenase and mitochondrial complex I) is the first large protein complex of the respiratory chains of many organisms from bacteria to humans. It catalyzes the ...

complex, located in the mitochondrial inner membrane. It is also known as Complex I and is the largest of the five complexes of the

electron transport chain An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples th ...

Gene

The NDUFB8 gene is located on the q arm of chromosome 10 in position 24.31 and is 6,194 base pairs long.

Structure

The NDUFB8 protein weighs 22 kDa and is composed of 186 amino acids. NDUFB8 is a subunit of the enzyme

, the largest of the respiratory complexes. The structure is L-shaped with a long, hydrophobic transmembrane domain and a hydrophilic domain for the peripheral arm that includes all the known redox centers and the NADH binding site.

NDUFB7 NADH dehydrogenase biquinone1 beta subcomplex subunit 7, also known as complex I-B18, is an enzyme that in humans is encoded by the ''NDUFB7'' gene. NADH dehydrogenase (ubiquinone) 1 beta subcomplex subunit 7 is an accessory subunit of the NADH d ...

and NDUFB8 have been shown to localize at the intermembrane surface of complex I. It has been noted that the

N-terminal The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

hydrophobic domain has the potential to be folded into an

alpha helix The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues e ...

spanning the inner

mitochondrial membrane A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used t ...

with a C-terminal hydrophilic domain interacting with globular subunits of Complex I. The highly conserved two-domain structure suggests that this feature is critical for the protein function and that the hydrophobic domain acts as an anchor for the

complex at the inner mitochondrial membrane.

Function

The protein encoded by this gene is an accessory subunit of the multisubunit NADH:ubiquinone oxidoreductase ( complex I) that is not directly involved in catalysis. Mammalian complex I is composed of 45 different subunits. It locates at the mitochondrial inner membrane. This protein complex has NADH dehydrogenase activity and oxidoreductase activity. It transfers electrons from NADH to the respiratory chain. The immediate electron acceptor for the enzyme is believed to be ubiquinone.

Alternative splicing Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be ...

occurs at this locus and two transcript variants encoding distinct isoforms have been identified. Initially, NADH binds to Complex I and transfers two electrons to the isoalloxazine ring of the flavin mononucleotide (FMN) prosthetic arm to form FMNH₂. The electrons are transferred through a series of iron-sulfur (Fe-S) clusters in the prosthetic arm and finally to coenzyme Q10 (CoQ), which is reduced to ubiquinol (CoQH₂). The flow of electrons changes the redox state of the protein, resulting in a conformational change and p''K'' shift of the ionizable side chain, which pumps four hydrogen ions out of the mitochondrial matrix.

Gene

Structure

Function

References

Further reading