The subcellular distribution of beta-carotene in bovine corpus luteum

Abstract The distribution of β-carotene was determined in various subcellular fractions of bovine corpus luteum. It was found in significant amounts in all subcellular fractions examined including nuclear, mitochondrial, microsomal, cytosolic, and floating lipid. Much of the β-carotene found in the crude nuclear and mitochondrial fractions was loosely bound and could be removed with repeated washings. In contrast, the microsomal β-carotene could only be removed by detergent extraction suggesting that it is an integral component of this membrane preparation. In the cytosol fraction β-carotene was bound to high-molecular-weight protein(s), quite possibly a plasma-derived lipoprotein. The subcellular distribution of β-carotene in corpus luteum is quite similar to the distribution of its metabolite, retinol, in liver. This finding coupled with other recently published data suggests that β-carotene could play a distinct role in corpora lutea function.