Lipids of subcellular particles

Abstract

Methods for isolation and characterization of subeellular particles as well as procedures for analysis of lipid class composition are discussed. The literature on distribution of lipids in subcellular particles is then reviewed. Pertinent new data from our laboratories are presented as well. The isolated particles are related to the organelles to which they correspond in the cell and are discussed with regard to heterogeneity and morphological integrity. Confusion can arise with regard to subcellular particles unless it is appreciated that: 1) preparation of particles of high purity generally requires more than the classical differential centrifugation scheme (both differential and gradient centrifugation may be required); 2) it is hazardous to apply exactly the same procedure for all tissues; 3) all subcellular fractions must be thoroughly characterized.The more recently devised DEAE cellulose column and thin-layer chromatographic procedures for analysis of lipid class composition are more reliable than the older hydrolytic or silieic acid column or paper chromatographic techniques. Endoplasmic Reticulum and Ribosomes (The Microsomal l~raction)

Phospholipids in artificially induced muscular dystrophy of calves

“…In the present study, biochemical analysis of the phospholipids in these tissues did not reveal any significant differences in the phospholipid composition of the heart muscle, whereas in the skeletal muscle the concentration of sphingomyelin increased and that of cardiolipin decreased in the degenerated tissue ( Table I). Cardiolipin is a phospholipid that occurs almost exclusively in mitochondria, whereas sphingomyelin is mainly extramitochondrial (Fleischer & Rouser, 1965). The decrease in the amount of cardiolipin points to preferential destruction of mitochondria, confirming the electron-microscopical studies.…”

Current Models for the Structure of Biological Membranes

“…In some cells (e .g ., plant cells) a large part of the lipid may be glycolipid (17), in mammalian cells the percentage is usually much smaller . A neutral lipid often occurring in considerable quantity is cholesterol ; carotenoids and quinones may also be present (90,230) . Small amounts of sugar bound to protein are usually found (on the order of 1-5% of the dry weight ; cf.…”

“…For instance, endoplasmic reticulum or mitochondria, which consistently show a narrower unit membrane than the cell membrane, contain lipids with shorter and more highly unsaturated fatty acids than the plasma membrane or the myelin sheath (for a review see Fleischer and Rouser [90]) . The thickness of the dense layers of the unit membrane varies considerably according to the heavy metal used in the fixation and staining procedures .…”

The Properties of Mitochondria Enriched in vitro with Cholesterol

“…The levels of sterol vary very widely amongst the membranes of animal cells being in general high in plasma membranes and low in intracellular membranes such as mitochondria [4,5]. Nevertheless, the small amount of sterol in mitochondria (about 3-60/, of the lipid [6]) seems to be important [2].…”