IDENTIFICATION OF THE NONSPECIFIC LIPID TRANSFER PROTEIN (STEROL CARRIER PROTEIN-2) IN PEROXISOMES OF LUNG TYPE-II CELLS

In view of the proposed role of the non-specific lipid-transfer protei n (nsL-TP; sterol carrier protein 2) in the metabolism of pulmonary su rfactant lipids (Batenburg et al. (1994) Biochem. J. 298, 223-229), it s subcellular localization was studied in the surfactant producing alv eolar type II cells. It was shown by immuno-electron microscopy that n sL-TP colocalizes with the peroxisomal marker catalase. The peroxisoma l localization of nsL-TP was confirmed by gradient fractionation of ty pe II cell homogenates. As a peroxisomal marker acyl-CoA:dihydroxyacet one-phosphate acyltransferase was assayed. Given this subcellular loca lization, it is very unlikely that nsL-TP plays a role in the transfer of surfactant lipids from the endoplasmic reticulum to the lamellar b odies. These results strengthen the opinion that peroxisomes are invol ved in surfactant synthesis. (C) 1994 Academic Press, Inc.