Palmitic is the main fatty acid carried by lipids of detergent-resistant membrane fractions from neural and non-neural cells

Lipids extracted from detergent-resistant membrane fractions, thought to derive from membrane domains, were analyzed for fatty acid composition. The proportion of palmitic acid in fractions isolated from neurons (cerebellar granule cells) and from neural-like cell lines (neuroblastoma-glioma NG108-15) nearly doubled (reaching about 54% of total fatty acids) with respect to cell WCL, indicating their enrichment in palmitic acid-carrying lipids. The proportion of palmitic acid in detergent-resistant fractions obtained from caveolin-transfected NG108-15 cells was comparable with that obtained from caveolin-negative cells, ruling out a specific role of this protein in recruiting palmitoylated lipid species. The enrichment in palmitic acid was remarked also in membrane fractions isolated from non-neuronal cell lines (A431) using either detergents or detergent-free techniques. Lipid fractionation and mass spectrometry experiments show that palmitic acid-rich phosphatidylcholine species are responsible of the peculiar fatty acid composition of these fractions. All together these results suggest that the enrichment in palmitic acid-rich phosphatidylcholine species is a common feature of neural and non-neural cell lines and may play a major role in the biogenesis of membrane domains.