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Ubiquinol-cytochrome c reductase binding protein
External IDs OMIM191330 MGI3646665 HomoloGene38164 ChEMBL: 1671612 GeneCards: UQCRB Gene
EC number
Species Human Mouse
Entrez 7381 67530
Ensembl ENSG00000156467 ENSMUSG00000021520
UniProt P14927 Q9D855
RefSeq (mRNA) NM_001199975 NM_026219
RefSeq (protein) NP_001186904 NP_080495
Location (UCSC) Chr 8:
97.24 – 97.25 Mb
Chr 13:
66.9 – 66.91 Mb
PubMed search [1] [2]

Ubiquinol-cytochrome c reductase binding protein, also known as UQCRB, is a protein which in humans is encoded by the UQCRB gene.[1]


The ubiquinone-binding protein is a nucleus-encoded component of ubiquinol-cytochrome c oxidoreductase (Complex III; EC in the mitochondrial respiratory chain and plays an important role in electron transfer as a complex of ubiquinone and QP-C. Complex III consists of 10 nuclear-encoded subunits and 1 mitochondrial-encoded subunit.[1]

UQCRB is a subunit of the respiratory chain protein Ubiquinol Cytochrome c Reductase (UQCR, Complex III or Cytochrome bc1 complex), which consists of the products of one mitochondrially encoded gene:

and ten nuclear genes:

After processing the cleaved leader sequence of the iron-sulfur protein is retained as subunit 9, giving 11 subunits from 10 genes.

The bovine gene product (subunit 6) was sequenced under the name "ubiquinone-binding protein", however there is little or no evidence for a role in ubiquinone binding. Subunit 7 was identified as a Q-binding protein by photo-labeling with a ubiquinone analog (subsequent structures show it to be exposed to the lipid phase but not involved in either Q-binding site). Subunits 6 and 7 reverse position on going from Laemli gels to Weber&Osborne gels, and one might suspect the name "Q-binding protein" arose from confusion with subunit 7. I have been told however that this is not the case, and both proteins were separately identified as Q-binding proteins. Genome anotators improved the situation by naming its gene "UQCR binding", UQCRB.


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