The subcellular distribution of carotenoids in Phycomyces blakesleeanus C115 car-42 mad-107 (--).

1. Subcellular fractions of the C115 car-42 mad-107(--) strain of Phycomyces blakesleeanus, prepared by differential centrifugation, were irreversibly associated with extraneous lipids. Such contamination was avoided by the use of density gradient centrifugation. 2. The two beta-carotene-containing fractions, a particulate fraction and lipid globules, also contained sterol, phospholipid and alkaline p-nitrophenylphosphatase activity. Both fractions revealed close similarities on amino acid analysis.