Beta,beta-carotene 9',10'-oxygenase 2 (BCO2)

Beta,beta-carotene 9',10'-oxygenase 2 (BCO2) is a mitochondrial enzyme responsible for the asymmetric (eccentric) oxidative cleavage of a wide variety of carotenoids, including both provitamin A carotenes and non-provitamin A xanthophylls like lutein and zeaxanthin. Located in the inner mitochondrial membrane, BCO2 serves as a critical gatekeeper that prevents the excessive accumulation of carotenoids, which can otherwise disrupt mitochondrial respiration and trigger oxidative stress. While its paralog BCO1 primarily produces retinal for the visual cycle, BCO2 generates various apocarotenoids and ionones that act as signaling molecules and alternative precursors for vitamin A. Genetic deficiency or mutations in BCO2 are linked to metabolic disorders such as hepatic steatosis and obesity, as well as the 'yellow fat' phenotype in livestock due to carotenoid deposition. In humans, the relative inactivity of BCO2 in the retina is hypothesized to be a specialized mechanism allowing for the protective accumulation of macular pigments. Although no drugs are currently approved to target BCO2, it is an area of active research for its potential roles in treating age-related macular degeneration and metabolic inflammation.

Other names

BCDO2B-DIOX-IIBeta-carotene dioxygenase 2Carotenoid-9',10'-cleaving dioxygenaseCarotenoid-cleaving dioxygenase mitochondrialBeta-carotene 9',10'-monooxygenase

Modulation of enzymatic oxidative cleavage of carotenoids to regulate tissue pigment levels, prevent mitochondrial oxidative stress, and generate bioactive apocarotenoid signaling molecules.