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PubMed1991

Glycosyl-phosphatidylinositol/inositol phosphoglycan: a signaling system for the low-affinity nerve growth factor receptor.

Nerve growth factor (NGF) exerts a variety of actions during embryonic development. At the early stages of inner ear development, NGF stimulates cell proliferation, an effect mediated through low-affinity receptors. We have studied the possibility that the glycosyl-phosphatidylinositol/inositol phosphoglycan (glycosyl-PtdIns/IPG) system is involved in transmitting this NGF signal. Endogenous glycosyl-PtdIns was characterized in extracts of cochleovestibular ganglia (CVGs) that incorporated [3H]glucosamine, [3H]galactose, [3H]myristic acid, and [3H]palmitic acid. Incubation of CVG with NGF produced a rapid and transient hydrolysis of glycosyl-PtdIns. Hydrolysis was complete at 100 ng/ml, and the half-maximal effect occurred at 25 ng/ml, overlapping with the concentration dependence of the mitogenic effect of NGF. An IPG was isolated from embryonic extracts. It had biological effects similar to those reported for the insulin-induced IPG in other tissues. It exerted a powerful mitogenic effect on CVG, comparable to that of NGF. Both the IPG- and NGF-induced cell proliferation were blocked by anti-IPG antibodies that recognized the endogenous IPG on a silica plate immunoassay. These results show that CVG possesses a fully active glycosyl-PtdIns/IPG signal transduction system and that the proliferative effects associated with NGF binding to low-affinity receptors require IPG generation.

Animals↗
PubMed1993

Effects of high-fat diet on incidence of spontaneous tumors in Wistar rats.

In a 2.5-year carcinogenicity study, two groups, both including male and female Wistar rats, were fed two different diets with 4% and 16% fat. In addition to 4% soybean oil, the high-fat diet contained 12% mono- and diglycerides, of which 85% was stearic acid and 13% palmitic acid. There was no difference in food consumption, body weight, weight gain, and longevity between the two groups. A statistically significant increase in the incidence of tumors in the high-fat group was seen in fibroadenoma of the mammae (female, p = 0.05). No statistically significant difference was seen when the incidence of benign mammary tumors (adenomas and fibroadenomas) was combined, just as the overall incidence of mammary tumors (adenomas, fibroadenomas, and adenocarcinomas) was not significantly different between the groups. A statistically significant decrease in the incidence of tumors in the high-fat group was seen in adenoma of the parathyroid gland (male, p = 0.04) and medullary carcinoma of the adrenal gland (male, p = 0.04). Combining the incidence of benign and malignant tumors of the adrenal medulla led to a further increase in the level of significance (p = 0.02). The present study showed that a high-fat diet influenced the tumor incidence in certain organs of rats. However, the overall differences in tumor incidence between rats fed the low- and the high-fat diet are considered marginal. Therefore we were not able to confirm or deny the hypothesis that a high-fat diet promotes the development of cancer. It should be noted that, in our study, fat accounted for about 30% of the total energy in the high-fat diet. This is much below the amount of fat normally found in the western diet but corresponds well to the level recommended for human intake. In addition, the rats fed the high-fat diet did not gain more weight, even though no difference was recorded in food consumption (g/kg body wt) between the groups.

Adenofibroma↗
PubMed1998

Distinct effects of fatty acids on translocation of gamma- and epsilon-subspecies of protein kinase C.

Effects of fatty acids on translocation of the gamma- and epsilon-subspecies of protein kinase C (PKC) in living cells were investigated using their proteins fused with green fluorescent protein (GFP). gamma-PKC-GFP and epsilon-PKC-GFP predominated in the cytoplasm, but only a small amount of gamma-PKC-GFP was found in the nucleus. Except at a high concentration of linoleic acid, all the fatty acids examined induced the translocation of gamma-PKC-GFP from the cytoplasm to the plasma membrane within 30 s with a return to the cytoplasm in 3 min, but they had no effect on gamma-PKC-GFP in the nucleus. Arachidonic and linoleic acids induced slow translocation of epsilon-PKC-GFP from the cytoplasm to the perinuclear region, whereas the other fatty acids (except for palmitic acid) induced rapid translocation to the plasma membrane. The target site of the slower translocation of epsilon-PKC-GFP by arachidonic acid was identified as the Golgi network. The critical concentration of fatty acid that induced translocation varied among the 11 fatty acids tested. In general, a higher concentration was required to induce the translocation of epsilon-PKC-GFP than that of gamma-PKC-GFP, the exceptions being tridecanoic acid, linoleic acid, and arachidonic acid. Furthermore, arachidonic acid and the diacylglycerol analogue (DiC8) had synergistic effects on the translocation of gamma-PKC-GFP. Simultaneous application of arachidonic acid (25 MicroM) and DiC8 (10 microM) elicited a slow, irreversible translocation of gamma-PKC- GFP from the cytoplasm to the plasma membrane after rapid, reversible translocation, but a single application of arachidonic acid or DiC8 at the same concentration induced no translocation. These findings confirm the involvement of fatty acids in the translocation of gamma- and epsilon-PKC, and they also indicate that each subspecies has a specific targeting mechanism that depends on the extracellular signals and that a combination of intracellular activators alters the target site of PKCs.

Animals↗
PubMed2002

Dietary stearic acid alters gallbladder bile acid composition in hamsters fed cereal-based diets.

Dietary stearic acid (18:0) lowers plasma and liver cholesterol concentration by reducing intestinal cholesterol absorption. We tested the hypothesis that dietary 18:0 reduces cholesterol absorption by altering hepatic bile acid synthesis and gallbladder bile acid composition. Male Syrian hamsters were fed modified NIH-07 open formula diets, enriched (5 g/100 g diet) in one of the following fatty acids: 18:0, palmitic acid (16:0), trans fatty acids (18:1t), oleic acid (18:1c) or linoleic acid (18:2). After 18 wk, gallbladders were removed and bile acid composition determined by HPLC. The distribution of primary bile acids (mol/100 mol) was unaffected by treatment. In contrast, dietary 18:0 significantly reduced the proportion of hydrophobic secondary bile acids, resulting in a lower hydrophobicity index of the bile. These data suggest that reduced cholesterol absorption by dietary 18:0 is due, at least in part, to reduced cholesterol solubility. The data further suggest that 18:0 may have altered the microflora populations that synthesize secondary bile acids. Although cholesterol 7alpha-hydroxylase (CYP7A1) activity was significantly higher in hamsters fed 18:0 compared with 16:0, this finding is most likely due to increased fecal bile acid output in the 18:0 group rather than transcriptional regulation of CYP7A1 by 18:0 or specific bile acids.

Animals↗
PubMed1997

Inclusion of coconut oil in diets for turkey breeders and its effects on embryonic yolk and liver fatty acids.

Turkey hens were fed either a standard breeder diet (CON, myristic acid, C14.0, 1.1%; palmitic acid, C16:0, 16.8%; oleic acid, C18:1, 23%; linoleic acid, C18:2, 48.7%) or a diet containing 5% coconut oil (COCO) enriched with medium chain fatty acids (MCFA; lauric acid, C12:0, 22.6%; C14:0, 10.8%; C16:0, 12.5%; C18:1, 14.8%; C18:2, 24.6%). After 10 d on the diets, fresh eggs were collected for yolk lipid and fatty acid (FA) determination. An additional 60 to 95 eggs were incubated and the FA profiles of the neutral lipid (NL) and phospholipid (PL) fractions of yolk sac and liver lipids were determined. The NL fraction of the yolk sac from CON eggs contained less C12:0 (0 vs 0.49%) and C14:0 (0.7 vs 4.6%) and more C18:1 (41.3 vs 37.5%). The PL fraction of the yolk sac from both treatments contained < 1% C14:0, and there was less than a 2% difference between treatments in other FA concentrations. The hepatic NL fraction from both treatments contained < 1% C14:0 and only C18:1 showed > 1% differences between treatments (Control = 59.9%; COCO = 56.62%). There were no dietary effects on the FA profile of hepatic PL. The presence of only minimal quantities of MCFA in hepatic NL and PL suggests that absorbed yolk sac MCFA are extensively metabolized during embryonic development.

Analysis of Variance↗
PubMed1988

Changes in lipid contents and fatty acid compositions in ovine corpora lutea during the estrous cycle and early pregnancy.

Changes in lipid contents and fatty acid compositions of each lipid fraction were examined in corpora lutea from 34 unmated ewes between Days 8 and 16 of the estrous cycle and from 6 ewes at Day 16 of pregnancy. Four patterns were observed during advancement of the estrous cycle. Luteal concentrations of free cholesterol and triglyceride (neutral lipids) increased between Days 14 and 16, during luteal regression, in a manner approximated by exponential functions of time, whereas luteal concentrations of phospholipid (polar lipids) increased and then decreased between Days 8 and 16 in a manner approximated by a sin function of time. Likewise, within the various lipid class component fatty acids, changes in palmitic acid weight percentages were approximated by sin functions of time, whereas arachidonic acid weight percentages increased between Days 14 and 16 in a manner approximated by exponential functions of time. Pregnancy either inhibited or reversed the changes in luteal lipid profiles, especially arachidonic acid percentages, between Days 14 and 16 of the estrous cycle. Luteal lipid profiles of corpora lutea from Day 16 pregnant sheep approximated lipid profiles of corpora lutea recovered from sheep between Days 12 and 14 of the estrous cycle. Comparison of luteal lipid profiles after tissue incubations at either 0 or 37 degrees C for 2 h revealed an effect of reproductive status on fatty acid metabolisms at Day 16. Changes observed in luteal lipid contents and fatty acid compositions during advancement of the estrous cycle represent aspects of lutein cell maturation and impending senescence that can be inhibited or reversed by pregnancy.

Animals↗
PubMed1984

In Vitro Fatty Acid Synthesis and Complex Lipid Metabolism in the Cyanobacterium Anabaena variabilis: I. Some Characteristics of Fatty Acid Synthesis.

In vitro fatty acid synthesis was examined in crude cell extracts, soluble fractions, and 80% (NH(4))(2)SO(4) fractions from Anabaena variabilis M3. Fatty acid synthesis was absolutely dependent upon acyl carrier protein and required NADPH and NADH. Moreover, fatty acid synthesis and elongation occurred in the cytoplasm of the cell. The major fatty acid products were palmitic acid (16:0) and stearic acid (18:0). Of considerable interest, both stearoyl-acyl carrier protein and stearoyl-coenzyme A desaturases were not detected in any of the fractions from A. variabilis. The similarities and differences in fatty acid synthesis between A. variabilis and higher plant tissues are discussed with respect to the endosymbiotic theory of chloroplast evolution.

Journal Article↗
PubMed1990

Mechanism for the Activation of Plasma Membrane H-ATPase from Rice (Oryza sativa L.) Culture Cells by Molecular Species of a Phospholipid.

The activation of H(+)-ATPase solubilized from plasma membrane of rice (Oryza sativa L. var Nipponbare) culture cells was examined by the exogenous addition of various phospholipids, free fatty acids, glycerides, polar head groups of phospholipids and molecular species of phosphatidylcholine (PC). H(+)-ATPase activity appeared to be stimulated by phospholipids in the following order: asolectin > phosphatidylserine > PC > lysophosphatidylcholine > phosphatidylglycerol, and maximal ATPase activation was noted at around 0.05 to 0.03% (w/v) of asolectin or molecular species of PC. Polar head groups such as glycerol, inositol, and serine only slightly activated ATPase activity or not at all, while ethanolamine and choline had no effect. Activation was dependent on the degree of saturation or unsaturation of the fatty acyl chain and its length. The activity decreased with increase in the length of fatty acyl chain from dimyristoryl(14:0)-PC to distearoyl(18:0)-PC and the degree of unsaturation from dioleoyl(18:1)-PC to dilinolenoyl(18:3)-PC. Maximum activation was observed when PC possessing 1-myristoyl(14:0)-2-oleoyl(18:1) or 1-oleoyl-2-myristoyl was added to the reaction mixture. These data show that the activation of plasma membrane H(+)-ATPase by PC depends on a combination of saturated (myristic acid 14:0, palmitic acid 16:0, and stearic acid 18:0) and unsaturated (oleic acid 18:1, linoleic acid 18:2, and arachidonic acid 20:4) fatty acids at the sn-1 and sn-2 positions of the triglycerides.

Journal Article↗
PubMed1991

Tumour-necrosis-factor-mediated cytotoxicity is correlated with phospholipase-A2 activity, but not with arachidonic acid release per se.

L929, a murine fibrosarcoma cell line highly sensitive to the anti-proliferative and cytotoxic action of tumour necrosis factor (TNF), was used as a target cell in our studies. We [Suffys et al. (1987) Biochem. Biophys. Res. Commun. 149, 735-743], as well as others, have previously provided evidence that a phospholipase (PL), most probably a PL-A2-type enzyme, is likely to be involved in TNF-mediated cell killing. We now further document this conclusion and provide suggestive evidence that the enzyme activity specifically involved in TNF cytotoxicity differs from activities associated with the eventual cell death process itself or with non-toxic serum treatment. We also show that the 5,8,11,14-icosatetraenoic acid (arachidonic acid, delta 4 Ach) released by PL, and possibly metabolized, is unlikely to be a key mediator of the TNF-mediated cytotoxicity. These conclusions are based on the following experimental findings. 1. TNF treatment of cells, prelabelled for 24 h with [3H] delta 4Ach or [14C] delta 3Ach (delta 3Ach identical to 5,8,11-icosatrienoic acid) resulted in an early, time-dependent and concentration-dependent release of radioactivity in the supernatant preceding actual cell death. The extent of this response was moderate, albeit reproducible and significant. Analysis of the total lipid fraction from cells plus supernatant revealed that only release of arachidonic acid from phospholipids, but not its metabolization was induced by TNF. However, the release of less unsaturated fatty acids, such as linoleic acid (Lin) or palmitic acid (Pam), was not affected during the first hours after TNF addition. 2. An L929 subclone, selected for resistance to TNF toxicity, was found to be defective in TNF-induced delta 4Ach libration. 3. Interleukin-1 (IL1) was not cytotoxic for L929 and did not induce release of delta 4Ach. 4. Release of delta 4Ach was not restricted to TNF; the addition of serum to the cells also induced release of fatty acids into the medium. In this case, however, there was no specificity, as all fatty acids tested, including Lin and Pam, were released. 5. Inhibition of PL-A2 activity by appropriate drugs markedly diminished TNF-induced delta 4Ach release and resulted also in a strong decrease in TNF-induced cytotoxicity. 6. Other drugs, including serine protease inhibitors, which strongly inhibit TNF-induced cytotoxicity, also decreased the TNF-induced delta 4Ach release, whereas LiCl potentiated both TNF-mediated effects. 7. Protection of cells against TNF toxicity by means of various inhibitors was not counteracted by addition of exogenous fatty acids, including delta 4Ach.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Effects of arachidonic acid on glutamate and gamma-aminobutyric acid uptake in primary cultures of rat cerebral cortical astrocytes and neurons.

The effects of arachidonic acid on glutamate and gamma-aminobutyric acid (GABA) uptake were studied in primary cultures of astrocytes and neurons prepared from rat cerebral cortex. The uptake rates of glutamate and GABA in astrocytic cultures were 10.4 nmol/mg protein/min and 0.125 nmol/mg protein/min, respectively. The uptake rates of glutamate and GABA in neuronal cultures were 3.37 nmol/mg protein/min and 1.53 nmol/mg protein/min. Arachidonic acid inhibited glutamate uptake in both astrocytes and neurons. The inhibitory effect was observed within 10 min of incubation with arachidonic acid and reached approximately 80% within 120 min in both types of culture. The arachidonic acid effect was not only time-dependent, but also dose-related. Arachidonic acid, at concentrations of 0.015 and 0.03 mumol/mg protein, significantly inhibited glutamate uptake in neurons, whereas 20 times higher concentrations were required for astrocytes. The effects of arachidonic acid were not as deleterious on GABA uptake as on glutamate uptake in both astrocytes and neurons. In astrocytes, GABA uptake was not affected by any of the doses of arachidonic acid studied (0.015-0.6 mumol/mg protein). In neuronal cultures, GABA uptake was inhibited, but not to the same degree observed with glutamate uptake. Lower doses of arachidonic acid (0.03 and 0.015 mumol/mg protein) did not affect neuronal GABA uptake. Other polyunsaturated fatty acids, such as docosahexaenoic acid, affected amino acid uptake in a manner similar to arachidonic acid in both astrocytes and neurons. However, saturated fatty acids, such as palmitic acid, exerted no such effect. The significance of the arachidonic acid-induced inhibition of neurotransmitter uptake in cultured brain cells in various pathological states is discussed.

Animals↗
PubMed1990

Characterisation of a myristoyl CoA:glycylpeptide N-myristoyl transferase activity in rat brain: subcellular and regional distribution.

An enzyme activity in rat brain, capable of catalysing the transfer of myristic acid from myristoyl CoA to the amino terminus of synthetic peptides, has been characterised. The synthetic peptides used as substrates were one based on the N-terminal eight amino acids of cyclic AMP-dependent protein kinase and another hexadecapeptide based on the N-terminal sequence of p60src. This N-myristoyl transferase (NMT) activity, which is both peptide dependent and heat labile, occurs in rat brain at levels at least three times those found in other rat tissues. In the presence of both ATP and CoA the enzyme catalysed the transfer of myristic acid, but not palmitic acid, specifically to the N-terminal glycine of the peptides. Both peptide substrates exhibited Michaelis-Menten kinetics yielding Km values of 100 microM and 60 microM, and Vmax values of 5 and 14.8 pmol/min/mg for the cyclic AMP-dependent protein kinase peptide and src-derived peptides, respectively. The majority of the NMT activity was present in the cytosol of the brain homogenates, and there was evidence of an NMT inhibitory activity in both the particulate fraction of brain homogenates and in brain cytosol. NMT activity could also be demonstrated in the 100,000 g supernatant of lysed synaptosomes, and the synaptosomal membranes also exhibited an inhibitory activity on the soluble enzyme. Different brain areas exhibited different levels of the N-myristoyl transferase activity and there was a fivefold difference in the activity found in the most active area, the hippocampus, compared to spinal cord.

Acyltransferases↗
PubMed1987

Further characterization of carbohydrate-containing fractions from Trypanosoma mega.

Epimastigotes of Trypanosoma mega were submitted to phenol extraction after lipid extraction, providing an extract whose carbohydrate portion (30%) contained fucose, ribose, xylose, mannose, galactose, and glucose. The purified fraction recovered in the void volume of Bio Gel P-150 gave on SDS-PAGE a band of Mr approximately equal to 55,000 positive for protein and carbohydrate and a diffuse band strongly positive for carbohydrate and lipids (Mr approximately equal to 22,000). The structural analysis of the carbohydrate moiety of this fraction by GLC-MS indicated the presence of nonreducing end groups of fucopyranose, mannopyranose, and galactopyranose, 3-O- and 4-O-substituted and 2,3- and 2,4-di-O-substituted galactopyranosyl units. Extraction of this fraction with chloroform/methanol/water provided a soluble fraction that on SDS-PAGE gave rise to a carbohydrate and lipid-positive band (Mr approximately equal to 22,000). This fraction contained fucose, mannose, and galactose (1:1:1). As main branch points, 2,3-di-O-substituted galactopyranosyl units were present according to methylation data. Similar proportions of fucopyranosyl, mannopyranosyl, galactopyranosyl end units were present. The presence of lipids in this fraction was confirmed by methanolysis following isolation and characterization of the corresponding fatty acid methyl esters. Palmitic acid (16:0) and an 18:1 fatty acid were the predominant fatty acids.

Animals↗
PubMed1981

Effects of long-chain Fatty acids on growth of rumen bacteria.

The effects of low concentrations of long-chain fatty acids (palmitic, stearic, oleic, and vaccenic) on the growth of seven species (13 strains) of rumen bacteria were investigated. Except for Bacteroides ruminicola and several strains of Butyrivibrio fibrisolvens, bacterial growth was not greatly affected by either palmitic or stearic acids. In contrast, growth of Selenomonas ruminantium, B. ruminicola, and one strain of B. fibrisolvens was stimulated by oleic acid, whereas the cellulolytic species were markedly inhibited by this acid. Vaccenic acid (trans Delta11 18:1) had far less inhibitory effect on the cellulolytic species than oleic acid (cis Delta9 18:1). Inclusion of powdered cellulose in the medium appeared to reverse both inhibitory and stimulatory effects of added fatty acids. However, there was little carry-over effect observed when cells were transferred from a medium with fatty acids to one without. Considerable variation in response to added fatty acids was noted among five strains of B. fibrisolvens. In general, exogenous long-chain fatty acids appear to have little, if any, energy-sparing effect on the growth of rumen bacteria.

Journal Article↗
PubMed1968

Effect of lipid materials on the production of lipase by Torulopsis ernobii.

The yeast Torulopsis ernobii produced approximately 50 units of extracellular lipase (glycerol ester hydrolase, E.C. 3.1.1.3) per ml when grown in 30-liter fermentors at 33 C for 40 hr in a base medium at pH 5.0. The addition of fats, oils, triglycerides, or higher fatty acids to this medium at concentrations of 0.2 to 0.6% markedly increased production; twofold increases in yield were obtained when 0.2% olive oil or a mixture of 0.14% oleic acid and 0.04% palmitic acid was added. The production of lipase paralleled growth, and the role of lipid materials in augmenting lipase production appears to be related to cell growth.

Cryptococcus↗
PubMed2004

Relationship between structures and biological activities of mycoplasmal diacylated lipopeptides and their recognition by toll-like receptors 2 and 6.

The lipopeptide FSL-1 [S-(2,3-bispalmitoyloxypropyl)-Cys-Gly-Asp-Pro-Lys-His-Pro-Lys-Ser-Phe, Pam(2)CGDPKHPKSF] synthesized on the basis of the N-terminal structure of a Mycoplasma salivarium lipoprotein capable of activating normal human gingival fibroblasts to induce the cell surface expression of ICAM-1 revealed an activity to induce production of monocyte chemoattractant protein 1, interleukin-6 (IL-6), and IL-8. FSL-1 also activated macrophages to produce tumor necrosis factor alpha as the Mycoplasma fermentans-derived lipopeptide MALP-2 (Pam(2)CGNNDESNISFKEK), a potent macrophage-activating lipopeptide, did. The level of the activity of FSL-1 was higher than that of MALP-2. This result suggests that the difference in the amino acid sequence of the peptide portion affects the activity because the framework structure other than the amino acid sequence of the former is the same as that of the latter. To determine minimal structural requirements for the activity of FSL-1, the diacylglyceryl Cys and the peptide portions were examined for this activity. Both portions did not reveal the activity. A single amino acid substitution from Phe to Arg and a fatty acid substitution from palmitic acid to stearic acid drastically reduced the activity. Similar results were obtained in measuring the NF-kappaB reporter activity of FSL-1 to human embryonic kidney 293 cells transfected with Toll-like receptor 2 and 6, together with a NF-kappaB-dependent luciferase reporter plasmid. These results suggest that both the diacylglyceryl and the peptide portions of FSL-1 are indispensable for the expression of biological activities and for the recognition by Toll-like receptors 2 and 6 and that the recognition of FSL-1 by Toll-like receptors 2 and 6 appears to be hydrophobic.

Acylation↗
PubMed1964

EXTRACTION AND PURIFICATION OF ENDOTOXIN FROM ENTEROBACTERIACEAE: A COMPARISON OF SELECTED METHODS AND SOURCES.

Fukushi, K. (National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Mont.), R. L. Anacker, W. T. Haskins, M. Landy, K. C. Milner, and E. Ribi. Extraction and purification of endotoxin from Enterobacteriaceae: a comparison of selected methods and sources. J. Bacteriol. 87:391-400. 1964.-Endotoxins containing only 0.2% N (accounted for by amino sugars) and 2% ester- and amide-linked fatty acids (calculated as palmitic acid) were prepared from Salmonella enteritidis. These products were of high biological potency, and were rapidly destroyed by acid hydrolysis. Equally potent acid-susceptible products were derived from different strains of Escherichia coli and Serratia marcescens. No correlation was evident between potency and content of nitrogen, fatty acids, and hexosamine; however, low values for carbohydrate were invariably associated with reduced endotoxic activity. Factors such as strain, method of cultivation, and extraction procedure markedly affected the chemical composition and activity of primary extracts. Results are given which demonstrate significant advantages in the use of cell walls for the isolation and purification of endotoxins.

Carbohydrates↗
PubMed1968

Lipid composition of the electron transport membrane of Haemophilus parainfluenzae.

The principal lipids associated with the electron transport membrane of Haemophilus parainfluenzae are phosphatidylethanolamine (78%), phosphatidylmonomethylethanolamine (0.4%), phosphatidylglycerol (18%), phosphatidylcholine (0.4%), phosphatidylserine (0.4%), phosphatidic acid (0.2%), and cardiolipin (3.0%). Phospholipids account for 98.4% of the extractible fatty acids. There are no glycolipids, plasmalogens, alkyl ethers, or lipo amino acid esters in the membrane lipids. Glycerol phosphate esters derived from the phospholipids by mild alkaline methanolysis were identified by their staining reactions, mobility on paper and ion-exchange column chromatography, and by the molar glycerol to phosphate ratios. Eleven diacyl phospholipids can be separated by two-dimensional thin-layer chromatography. Each lipid served as a substrate for phospholipase D, and had a fatty acid to phosphate ratio of 2:1. Each separated diacyl phospholipid was deacylated and the glycerol phosphate ester was identified by paper chromatography in four solvent systems. Of the 11 separated phospholipids, 3 were phosphatidylethanolamines, 2 were phosphatidylserines, and 2 were phosphatidylglycerols. Phosphatidylcholine, cardiolipin, and phosphatidic acid were found at a single location. Phosphatidylmonomethylethanolamine was found with the major phosphatidylethanolamine. Three distinct classes of phospholipids are separable according to their relative fatty acid compositions. (i) The trace lipids consist of two phosphatidylethanolamines, two phosphatidylserines, phosphatidylcholine, phosphatidic acid, and a phosphatidylglycerol. Each lipid represents less than 0.3% of the total lipid phosphate. These lipids are characterized by high proportions of the short (C(10) to C(14)) and long (C(19) to C(22)) fatty acids with practically no palmitoleic acid. (ii) The major phospholipids (93% of the lipid phosphate) are phosphatidylethanolamine, phosphatidylmonomethylethanolamine, and phosphatidylglycerol. These lipids contain a low proportion of the short ( C(19)) fatty acids. Palmitic and palmitoleic acids represent over 80% of the total fatty acids. (iii) The fatty acid composition of the cardiolipin is intermediate between the other two classes. Both palmitoleic and the longer fatty acids represent a significant proportion of the total fatty acid.

Chemistry Techniques, Analytical↗
PubMed1993

Site-directed mutations in the Sindbis virus E2 glycoprotein identify palmitoylation sites and affect virus budding.

The assembly and budding of Sindbis virus, a prototypic member of the alphavirus subgroup in the family Togaviridae, requires a specific interaction between the nucleocapsid core and the membrane-embedded glycoproteins E1 and E2. These glycoproteins are modified posttranslationally by the addition of palmitic acid, and inhibitors of acylation interfere with this budding process (M.J. Schlesinger and C. Malfer, J. Biol. Chem. 257:9887-9890, 1982). This report describes the use of site-directed mutagenesis to identify two of the acylation sites in the E2 glycoprotein as the cysteines near the carboxyl terminus of the protein which is oriented to the cytoplasmic domain of this type 1 transmembrane protein. Additional mutations were made at two prolines within a hydrophobic sequence of E2 that is highly conserved among several alphaviruses, and the mutant viruses were aberrant in assembly and particle formation. These data support earlier studies indicating that the native structure of the cytoplasmic domain of E2 is essential for proper assembly of this enveloped virus.

Amino Acid Sequence↗