van Heusden G P, Bos K, Raetz C R, Wirtz K W
Centre for Biomembranes and Lipid Enzymology, State University of Utrecht, The Netherlands.
J Biol Chem. 1990 Mar 5;265(7):4105-10.
Chinese hamster ovary cells deficient in intact peroxisomes were compared with wild type cells for the presence of the nonspecific lipid transfer protein (nsL-TP; sterol carrier protein 2). With the immunoblotting technique using the affinity purified antibody against rat liver nsL-TP, this protein was shown to be present in the homogenates from wild type cells, but could not be detected in mutant cells. In agreement with a previous study using livers from Zellweger patients it appears that there is a positive, as yet unknown, correlation between peroxisomes and the occurrence of nsL-TP in the cell. As a control using the affinity-purified antibody against the phosphatidylinositol transfer protein from bovine brain, levels of this protein were found to be normal in mutant cells. By use of metrizamide density gradients, nsL-TP was shown to cosediment with a membrane fraction different from peroxisomes. A protein of 58,000 daltons cross-reactive with the antibody against nsL-TP did cosediment with the peroxisomes in wild type cells and possibly with a "peroxisomal remnant" in the mutant cells. Incubation of wild type and mutant cells with L-[3-14C]serine showed that the biosynthesis of phosphatidylserine and the subsequent conversion into phosphatidylethanolamine was comparable in both cell types. This indicates that nsL-TP is not involved in the translocation of phosphatidylserine from the endoplasmic reticulum to the mitochondria as the site of decarboxylation.
