Evidence for compartmentalization of mammalian carotenoid metabolism

Grzegorz Palczewski, Jaume Amengual, Charles L. Hoppel, Johannes Von Lintig

Research output: Contribution to journalArticlepeer-review


The critical role of retinoids (vitamin A and its derivatives) for vision, reproduction, and survival has been well established. Vitamin A is produced from dietary carotenoids such as β-carotene by centric cleavage via the enzyme BCO1. The biochemical and molecular identification of a second structurally related P-carotene metabolizing enzyme, BCO2, has led to a prolonged debate about its relevance in vitamin A biology. While BCO1 cleaves provitamin A carotenoids, BCO2 is more promiscuous and also metabolizes nonprovitamin A carotenoids such as zeaxanthin into longchain apo-carotenoids. Herein we demonstrate, in cell lines, that human BCO2 is associated with the inner mitochondrial membrane. Different human BCO2 isoforms possess cleavable N-terminal leader sequences critical for mitochondrial import. Subfractionation of murine hepatic mitochondria confirmed the localization of BCO2 to the inner mitochondrial membrane. Studies in BCO2-knockout mice revealed that zeaxanthin accumulates in the inner mitochondrial membrane; in contrast, P-carotene is retained predominantly in the cytoplasm. Thus, we provide evidence for a compartmentalization of carotenoid metabolism that prevents competition between BCO1 and BCO2 for the provitamin and the production of noncanonical P-carotene metabolites.

Original languageEnglish (US)
Pages (from-to)4457-4469
Number of pages13
JournalFASEB Journal
Issue number10
StatePublished - Oct 1 2014
Externally publishedYes


  • BCO1
  • BCO2
  • Vitamin A
  • Zeaxanthin
  • β-carotene

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


Dive into the research topics of 'Evidence for compartmentalization of mammalian carotenoid metabolism'. Together they form a unique fingerprint.

Cite this