UQCRB

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

Structure
The gene product of UQCRB is a subunit of the respiratory chain protein Ubiquinol Cytochrome c Reductase (UQCR, is_associated_with::Complex III or Cytochrome bc1 complex; E.C. 1.10.2.2), which consists of the products of one mitochondrially encoded gene, MTCYTB (mitochondrial is_associated_with::cytochrome b) and ten nuclear genes: is_associated_with::UQCRC1, is_associated_with::UQCRC2, Cytochrome c1, is_associated_with::UQCRFS1 (is_associated_with::Rieske protein), UQCRB, "11kDa protein", is_associated_with::UQCRH (cyt c1 Hinge protein), Rieske Protein presequence, "cyt. c1 associated protein", and "Rieske-associated protein". After processing, the cleaved leader sequence of the iron-sulfur protein is retained as subunit 9, giving 11 subunits from 10 genes.

Function
The ubiquinone-binding protein is a nucleus-encoded component of ubiquinol-cytochrome c oxidoreductase (Complex III; EC 1.10.2.2) in the mitochondrial respiratory chain and plays an important role in electron transfer as a complex of ubiquinone and QP-C.

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 transfer from Laemli gels to Weber&Osborne gels, and one might suspect the name "Q-binding protein" arose from confusion with subunit 7. However, it has been claimed that both proteins were separately identified as Q-binding proteins. Genome annotators improved the situation by naming this gene "UQCR binding", or UQCRB.