NDUFB2

{{Short description|Protein-coding gene in the species Homo sapiens}}

NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 2, mitochondrial is an enzyme that in humans is encoded by the NDUFB2 gene.{{cite journal |vauthors=Emahazion T, Beskow A, Gyllensten U, Brookes AJ | title = Intron based radiation hybrid mapping of 15 complex I genes of the human electron transport chain | journal = Cytogenet Cell Genet | volume = 82 | issue = 1–2 | pages = 115–9 |date=Nov 1998 | pmid = 9763677 | doi =10.1159/000015082 | s2cid = 46818955 }}{{cite journal |vauthors=Loeffen JL, Triepels RH, van den Heuvel LP, Schuelke M, Buskens CA, Smeets RJ, Trijbels JM, Smeitink JA | title = cDNA of eight nuclear encoded subunits of NADH:ubiquinone oxidoreductase: human complex I cDNA characterization completed | journal = Biochem Biophys Res Commun | volume = 253 | issue = 2 | pages = 415–22 |date=Jan 1999 | pmid = 9878551 | doi = 10.1006/bbrc.1998.9786 }}{{cite web | title = Entrez Gene: NDUFB2 NADH dehydrogenase (ubiquinone) 1 beta subcomplex, 2, 8kDa| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=4708}} NADH dehydrogenase (ubiquinone) 1 beta subcomplex, 2, 8kDa is an accessory subunit of the NADH dehydrogenase (ubiquinone) 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.{{cite book | first1 = Donald | last1 = Voet | first2 = Judith G. | last2 = Voet | first3 = Charlotte W. | last3 = Pratt | name-list-style = vanc | author1-link = Donald Voet | author2-link = Judith G. Voet | title = Fundamentals of biochemistry: life at the molecular level | date = 2013 | publisher = Wiley | location = Hoboken, NJ | isbn = 978-0-470-54784-7 | chapter = Chapter 18 | pages = 581–620 | edition = 4th }}

Structure

The NDUFB2 gene, located on the q arm of chromosome 7 in position 34, is 9,966 base pairs long and is composed of 4 exons. The NDUFB2 protein weighs 12 kDa and is composed of 105 amino acids.{{cite journal | vauthors = Zong NC, Li H, Li H, Lam MP, Jimenez RC, Kim CS, Deng N, Kim AK, Choi JH, Zelaya I, Liem D, Meyer D, Odeberg J, Fang C, Lu HJ, Xu T, Weiss J, Duan H, Uhlen M, Yates JR, Apweiler R, Ge J, Hermjakob H, Ping P | title = Integration of cardiac proteome biology and medicine by a specialized knowledgebase | journal = Circulation Research | volume = 113 | issue = 9 | pages = 1043–53 | date = Oct 2013 | pmid = 23965338 | pmc = 4076475 | doi = 10.1161/CIRCRESAHA.113.301151 }}{{cite web | url = https://amino.heartproteome.org/web/protein/O95178 | work = Cardiac Organellar Protein Atlas Knowledgebase (COPaKB) | title = NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 1 }} NDUFB2 is a subunit of the enzyme NADH dehydrogenase (ubiquinone), 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. NDUFB3 is one of about 31 hydrophobic subunits that form the transmembrane region of Complex I. It has been noted that the N-terminal hydrophobic domain has the potential to be folded into an alpha helix spanning the inner mitochondrial membrane 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 NADH dehydrogenase (ubiquinone) complex at the inner mitochondrial membrane. Hydropathy analysis revealed that this subunit and 4 other subunits have an overall hydrophilic pattern, even though they are found within the hydrophobic protein (HP) fraction of complex I.

Function

The human NDUFB2 gene codes for a subunit of Complex I of the respiratory chain, which transfers electrons from NADH to ubiquinone. However, NDUFB2 is an accessory subunit of the complex that is believed not to be involved in catalysis.{{cite web|title=NDUFB2 - NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 2|url=https://www.uniprot.org/uniprot/O95178|website=UniProt: a hub for protein information|publisher=The UniProt Consortium|access-date=2 April 2015}} 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 pK shift of the ionizable side chain, which pumps four hydrogen ions out of the mitochondrial matrix.

NDUFB2

Structure

Function

References

Further reading