Biology:NDUFB2

Short description: Protein-coding gene in the species Homo sapiens

Generic protein structure example

NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 2, mitochondrial is an enzyme that in humans is encoded by the NDUFB2 gene. 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.

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. 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. 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.

Further reading

• "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)". Genome Res. 14 (10B): 2121–7. 2004. doi:10.1101/gr.2596504. PMID 15489334. 
• "Differential-display polymerase chain reaction identifies nicotinamide adenine dinucleotide-ubiquinone oxidoreductase as an ischemia/reperfusion-regulated gene in cardiomyocytes". Chest 125 (1): 228–35. 2004. doi:10.1378/chest.125.1.228. PMID 14718445. 
• "Human chromosome 7: DNA sequence and biology". Science 300 (5620): 767–72. 2003. doi:10.1126/science.1083423. PMID 12690205. Bibcode: 2003Sci...300..767S. 
• "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. 2003. doi:10.1073/pnas.242603899. PMID 12477932. Bibcode: 2002PNAS...9916899M. 
• "Cloning and functional analysis of cDNAs with open reading frames for 300 previously undefined genes expressed in CD34+ hematopoietic stem/progenitor cells". Genome Res. 10 (10): 1546–60. 2001. doi:10.1101/gr.140200. PMID 11042152. 
• Sanger Centre, The; Washington University Genome Sequencing Cente, The (1999). "Toward a complete human genome sequence". Genome Res. 8 (11): 1097–108. doi:10.1101/gr.8.11.1097. PMID 9847074. 

This article incorporates text from the United States National Library of Medicine, which is in the public domain.