Cytochrome b-c1 complex subunit 1, mitochondrial

UQCRC1 (Cytochrome b-c1 complex subunit 1, mitochondrial) is a core component of the ubiquinol-cytochrome c oxidoreductase complex (Complex III) within the mitochondrial electron transport chain (UniProt: P31930). It catalyzes electron transfer from ubiquinol to cytochrome c while driving proton translocation across the inner mitochondrial membrane, a process essential for oxidative phosphorylation and ATP synthesis. The protein also participates in processing of the Rieske iron-sulfur protein during Complex III assembly.

UQCRC1 is expressed in mitochondria-rich tissues and plays a particularly important role in maintaining proper mitochondrial function in nigral dopaminergic neurons (UniProt: P31930). Mutations in UQCRC1 are associated with parkinsonism with polyneuropathy (PKNPY; MIM 619279), an autosomal dominant disorder characterized by late-onset levodopa-responsive parkinsonism and sensorimotor polyneuropathy.

In Alzheimer's disease, UQCRC1 shows significant upregulation in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of +1.43 (Chaparral AD proteomics). This elevation suggests altered mitochondrial Complex III activity or composition in AD pathology, potentially reflecting compensatory responses to bioenergetic stress or mitochondrial dysfunction in affected neurons.