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Evaluation of levonorgestrel action on the flank organ and the sebaceous gland lipogenesis of female hamsters.

The role of testosterone and levonorgestrel action on the flank organ by measuring sebaceous gland lipogenesis of female hamsters by the metabolic incorporation of 14C-glucose were investigated. Also, a partial characterization of the radiolabeled lipid fraction was obtained. The effects of in vivo steroids administration were evaluated by 14C-U-glucose metabolic incorporation into lipids by the female hamster flank organs in culture conditions, in the presence or absence of LNG and/or T in the incubation medium. The radioactive lipids were identified by thin layer chromatography. Levonorgestrel alone or together with testosterone on female hamster flank organs decreased the organ weight and sebum content compared with T-treatment alone. In culture conditions, a rapid and significant increase of radiolabeled glucose was observed with T. By contrast when LNG was present in the incubation medium, no differences in 14C-U-glucose incorporation were observed when compared with their controls. When T+LNG were added, a similar result to the obtained when using LNG alone was determined. Testosterone increased glycerides and free fatty acids but decreased polar lipids; whereas LNG did not have any effect in the relative proportions of 14C-U-glucose incorporated into the different classes of lipids, when it was compared with their controls. The results indicated that LNG abolished the increasing effect of 14C glucose incorporation caused by T and changed the lipid composition induced on female hamsters flank organs.

Animals↗

Misregulation of maltose uptake in a glucose repression defective mutant of Saccharomyces cerevisiae leads to glucose poisoning.

In hex2 mutants of Saccharomyces cerevisiae, which are defective in glucose repression of several enzymes, growth is inhibited if maltose is present in the medium. After adding [14C]maltose to cultures growing with ethanol, maltose metabolism was followed in both hex2 mutant and wild-type cells. The amount of radioactivity incorporated was much higher in hex2 than in wild-type cells. Most of the radioactivity in hex2 cells was located in the low molecular mass fraction. Pulse-chase experiments showed that 2 h after addition of maltose, hex2 cells hydrolysed maltose to glucose, which was partially excreted into the medium. 31P-NMR studies gave evidence that turnover of sugar phosphates was completely abolished in hex2 cells after 2 h incubation with maltose. 13C-NMR spectra confirmed these results: unlike those for the wild-type, no resonances corresponding to fermentation products (ethanol, glycerol) were found for hex2 cells, whereas there were resonances corresponding to glucose. Although maltose is taken up by proton symport, the internal pH in the hex2 mutant did not change markedly during the 5 h after adding maltose. The intracellular accumulation of glucose seems to explain the inhibition of growth by maltose, probably by means of osmotic damage and/or unspecific O-glycosylation of proteins. Neither maltose permease nor maltase was over-expressed, and so these enzymes were not the cause of glucose accumulation. Hence, the coordination of maltose uptake, hydrolysis to glucose and glycolysis of glucose is not regulated simply by the specific activity of the catabolic enzymes involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport, Active↗

The synthesis of phosphatidylcholine by adult rat lung alveolar type II epithelial cells in primary culture.

1. The formation of phosphatidylcholine from radioactive precursors was studied in adult rat lung alveolar type II epithelial cells in primary culture. 2. The incorporation of [Me-14C]choline into total lipids and phosphatidylcholine was stimulated by addition of palmitate, whereas the incorporation of [U-14C]glucose into phosphatidylcholine and disaturated phosphatidylcholine was stimulated by addition of choline. Addition of glucose decreased the absolute rate of incorporation of [1(3)-3H]glycerol into total lipids, phosphatidylcholine and disaturated phosphatidylcholine, decreased the percentage [1(3)-3H]glycerol recovered in phosphatidylcholine, but increased the percentage phosphatidylcholine label in the disaturated species. 3. At saturating substrate concentrations, the percentages of phosphatidylcholine radioactivity found in disaturated phosphatidylcholine after incubation with [1-(14)C]acetate (in the presence of glucose) [1-(14)C]palmitate (in the presence of glucose), [Me-14C]choline (in the presence of glucose and palmitate) and [U-14C]glucose (in the presence of choline and palmitate) were 78, 75, 74 and 90%, respectively. 4. Fatty acids stimulated the incorporation of [U-14C]glucose into the glycerol moiety of phosphatidylcholine. The degree of unsaturation of the added fatty acids was reflected in the distribution of [U-14C]glucose label among the different molecular species of phosphatidylcholine. It is suggested that the glucose concentration in the blood as related to the amount of available fatty acids and their degree of unsaturation may be factors governing the synthesis of surfactant lipids.

Acetates↗

Studies on avian erythrocyte metabolism. XII. The synthesis and degradation of inositol pentakis (dihydrogen phosphate).

The pathway(s) of synthesis and degradation of inositol 1, 3, 4, 5, 6 pentakis (dihydrogen phosphate) (inositol-P5), found predominantly in the avian erythrocyte, are unknown. Myo-inositol (inositol), D-glucose, inosine, and phosphate have been studied as potential precursors of inositol-P5 synthesis in chicken erythrocytes. Whole blood from chickens at several ages has been incubated for prolonged periods and the concentration of inositol-P5 measured to determine the ability of the avian erythrocyte to catabolize inositol-P5. Incubation of erythrocyte suspensions from 5-day chicks with [U-14 C]myo-inositol (inositol) for 17 hr lead to the appearance of 19.8% of the radioactivity in the aqueous acid-soluble extract of the erythrocytes (RBC). Fractionation of this extract on an anion exchange column yielded five major radioactive peaks, three of which represent 1) free myo-inositol, accounting for 63.5% of the radioactivity; 2) myo-inositol monokis (dihydrogen phosphate) (inositol-P), representing 1.6% of the radioactivity; and 3) inositol 1, 3, 4, 5, 6 pentakis (dihydrogen phosphate) (inositol-P5), representing 27.0% of the label in the erythrocyte. Sodium fluoride did not inhibit the incorporation of [U-14 C]myo-inositol into inositol-P5. Similar incubations with D-[U-14 C]-glucose and [U-14 C]-inosine yielded no incorporation of radioactivity into inositol-P5. These data are consistent with the interpretation that inositol is the major precursor for synthesis of inositol-P5 in chick red cells. Incubation of whole blood from 1-, 5-, and 42-day chicks and mature birds at 40 C for as long as 72 hr resulted in increases in RBC inorganic phosphate (Pi) thought due primarily to depletion of adenosine triphosphate (ATP). Inositol-P5 content of RBC of 5- and 42-day birds decreased 28 and 20%, respectively, after 72 hr, but no change was noted in inositol-P5 levels of RBC from mature birds. The red cells of the mature bird appear to be unable to catabolize inositol-P5 at significant rates. The apparent inability of the chicken erythrocyte to alter readily its concentration of inositol-P5 suggests that the hemoglobin oxygen delivery system of birds may be less adaptable to changing oxygen requirements by regulating the concentration of hemoglobin modulator than is that of the mammals.

Adenosine Triphosphate↗

Hepatic contribution to newly made fatty acids in adipose tissue in rats and inhibition of hepatic and extrahepatic lipogenesis from glucose by dietary corn oil.

We have reexamined an earlier rat study in which the authors concluded that 60 min after [U-14C]-glucose injection half of labeled fatty acids found in adipose tissue had been made in liver and then transported to the adipose tissue. We have shown that even under conditions in which the lipogenic role of the liver is optimized (fed-refed rats on a fat-free, high-carbohydrate diet), almost none of the labeled fatty acids found in adipose tissue of rats 60 min after they were fed a labeled glucose test meal was derived from the liver. This conclusion was based experimentally on (a) the use of the blocking agent Triton WR 1339 to measure the total labeled triglyceride fatty acids (TGFA) synthesized and secreted by the liver in 60 min and (b) comparison of plasma TGFA-14C data with radioactivity found in liver and in adipose tissue in 60 min. Without using Triton WR 1339, mathematical, analysis of plasma TFGA-14C following the glucose test-meal leads one to the same conclusion: 97% of 14C-labeled fatty acids found in adipose tissue at 60 min was made in situ. Additional studies in rats established that the source of error in the earlier studies was an incorrect assumption that dietary corn oil could inhibit hepatic lipogenesis from glucose C without inhibiting fatty acid synthesis in adipose tissue. In our studies, 10% corn oil inhibited equally both hepatic and adipose tissue fatty acid synthesis from glucose C under conditions that precluded any significant transport of labeled TGFA-14C from liver to adipose tissue.

Adipose Tissue↗

Stimulation of glucose utilization in the rat claustrum by pain.

The involvement of the claustrum in processing of somatosensory information was investigated using the formalin test as an established pain test. The metabolic activity of the claustrum and other brain structures belonging to the somatosensory system was assessed by autoradiographic method of the uptake of (3H)-labelled 2-deoxyglucose (2-DG). Glucose utilization in the claustrum was stimulated by subcutaneous injection of formalin into the front paw. The increase of radioactivity was observed not only in the claustrum, but also in the anterior pretectum, the ventral thalamic nucleus, the somatosensory, insular and piriform cortices on the contralateral side to formalin stimulation. After stereotactical injection of morphine into the contralateral pretectum to stimulation side, uptake of 2-DG in the claustrum was abolished. These results indicate that the claustrum is an important relay nucleus in the somatosensory system, which may convey somatosensory information from the pretectum to the cerebral cortex, thus by-passing the thalamus, throughout the pretecto-claustro-cortical pathways.

Animals↗

Validation of an analytic method of calculating cerebral glucose metabolism using PET.

UNLABELLED: Quantitative modeling of cerebral metabolic rate for glucose (CMRglc) using PET with the FDG method requires calculation of the integral of the time course of radioactivity in arterial plasma. Numeric integration has typically been used but requires 30 or more blood samples taken between 15 s and 100 min after injection of the radiotracer. Our laboratory has developed an alternative integration method that fits the values of the plasma samples to an analytically integrable function using only 4-6 samples taken between 40 and 110 min after radiotracer injection. METHODS: The plasma integrals were calculated by both the analytic and the numeric methods with data from FDG PET studies that were not used in the development of the analytic method. In 39 PET studies from 22 healthy volunteers, 30 plasma samples were taken over 110 min. RESULTS: The plasma integrals determined by the analytic and numeric methods yielded a within-subject correlation coefficient of >0.95 and differences of <10%. CONCLUSION: Because the analytic method requires less blood sampling and does not require sampling immediately after radiotracer injection, the experimental procedure is simplified without loss of accuracy in CMRglc computation, and the effect of missing or incorrect samples is reduced.

Adult↗

Spontaneous glycosylation of glycosaminoglycan substrates by adherent fibroblasts.

SV40-transformed mouse fibroblasts migrate upon, and spontaneously glycosylate, plastic substrates derivatized with chondroitin-6 sulfate and hyaluronic acid. Autoradiography of cultures prelabeled with 3H-glucose and 3H-galactose demonstrates the presence of silver grains near adherent cells. Silver grains are particularly dense near cells cultured on chondroitin sulfate. No significant grains are observed on control dishes or dishes derivatized with polygalacturonic acid. Radioactive material left by cells is not removed by boiling the dishes in 8 M urea and 10% sodium dodecylsulfate, suggesting that it is covalently linked to the derivatized plastic. Acid hydrolysis shows that the radioactive material consists of glucuronic acid and N-acetylglucosamine when the prelabeled cells are cultured on hyaluronic acid. When cells are cultured on chondroitin sulfate, the radioactive product consists only of glucuronic and and N-acetylgalactosamine sulfate. Sonicates of prelabeled cells or the supernatants from cultures of intact prelabeled cells add no SDS-urea-resistant radioactivity to dishes derivatized with these glycosaminoglycans.

Animals↗

Long-term population dynamics and in situ physiology in activated sludge systems with enhanced biological phosphorus removal operated with and without nitrogen removal.

Quantitative fluorescence in situ hybridization (FISH) and the combination of FISH with microautoradiography (MAR) were used in order to study the long-term population dynamics (2.5 years) and the in situ physiology in two parallel activated sludge pilot systems with enhanced biological phosphorus removal (EBPR). The two systems received the same influent wastewater, but were differently operated (with and without nitrogen removal, respectively). Both systems showed a significant P removal that increased when different substrates (phosphorus (P), acetate and glucose, respectively) were added to the influent wastewater. Rhodocyclus-related bacteria were present in both systems in significant numbers (ranging from 4 to 28%) throughout the whole period. This supports the hypothesis that these bacteria occur in significant numbers in different types of well-operating EBPR activated sludge processes. However, we observed a lower correlation (< 0.5) for the amount of Rhodocyclus-related bacteria to the P content in activated sludge than previous studies (> 0.9). The Actinobacteria were the only additional group of bacteria which showed a similar degree of correlation to the P content in activated sludge as the Rhodocyclus-related bacteria--but only for the system without nitrogen removal. Significant amounts (< or = 12%) of glycogen-accumulating bacteria (GAOs) were detected in the system with nitrogen removal (but not in the other system), but had no, in contrast to previous observations, apparent negative effect on the overall EBPR performance. FISH-MAR indicated that a significant part of the Betaproteobacteria (part of them identified as Rhodocyclus-related bacteria) as well as the Actinobacteria were able to take up 33Pi, [3H]-acetate and [3H]-glucose under anaerobic-aerobic conditions. The contribution of anoxic 33Pi uptake under alternating anaerobic-anoxic conditions was significantly lower. Interestingly, not all Rhodocyclus-related bacteria showed uptake of these three radioactive substrates. This may be due to differences in metabolic state, physiological potential or genotype, not detectable by the present probe set for Rhodocyclus-related bacteria. Comparison of the 33Pi, [3H]-acetate and [3H]-glucose uptake by activated sludge after different fixation and incubation procedures showed that a part of the observed 33Pi uptake may have been caused by a combination of a biological and chemical or biologically induced chemical P adsorption.

Archaea↗

A standardized blood sampling scheme in quantitative FDG-PET studies.

Quantitative estimation of brain glucose metabolism (rCMRGlc) with positron emission tomography and fluorodeoxyglucose involves arterial blood sampling to estimate the delivery of radioactivity to the brain. Usually, for an intravenous injection of 30 s duration, an accurate input curve requires a frequency of one sample every 5 s or less to determine the peak activity in arterial plasma during the first 2 min after injection. In this work, 13 standardized sampling times were shown to be sufficient to accurately define the input curve. This standardized input curve was subsequently fitted by a polynomial function for its rising part and by spectral analysis for its decreasing part. Using the measured, the standardized, and the fitted input curves, rCMRGlc was estimated in 32 cerebral regions of interest in 20 normal volunteers. Comparison of rCMRGlc values obtained with the measured and the fitted input curves showed that both procedures gave consistent results, with a maximal relative error in mean rCMRGlc of 1% when using the autoradiographic method and 2% using kinetic analysis of dynamic data. This input-curve-fitting technique, which is not dependent on the peak time occurrence, allows an accurate determination of the input-curve shape from reduced sampling schemes.

Adult↗

Effect of hypoxia and ischemia on the distribution of protein in brain cellular fractions.

The effect of postdecapitative ischemia (5 min at 37 degrees) and hypoxia (5% O2, 95% N2, 30 min) on the distribution of protein radioactivity in the cellular fractions of guinea pig cerebral cortex was studied. Ischemic conditions resulted in the increase of total radioactivity level and protein content in the mitochondrial fraction. In the cytosol the opposite effect was observed; the radioactivity and protein content were decreased. The amino acid analysis of microsomal proteins and the distribution of glucose-6-phosphatase activity, differing from those in control animals, suggest structural disturbances in the microsomal fraction. The results indicate a different sedimentation of proteins in the given experimental conditions. After hypoxia such effects were not observed.

Amino Acids↗

Visualization of prostate cancer with 11C-choline positron emission tomography.

BACKGROUND AND OBJECTIVE: Visualization of prostate cancer with positron emission tomography (PET) using 2-[18F]-2-deoxy-D-glucose (FDG) as radiopharmaceutical is limited by the low uptake of FDG in the tumor and by radioactivity excreted into the bladder. More specific PET radiopharmaceuticals would be welcome. Carbon-11 labeled choline (CHOL) is a new radiopharmaceutical potentially useful for tumor imaging as it is incorporated in the cell membranes as phosphatidylcholine. We prospectively studied the visualization of prostate cancer using CHOL PET. METHODS: A total of 25 consecutive patients with histologically proven prostate cancer and five patients with a benign prostate were included. PET images were performed with an ECAT HR(+) using 400MBq CHOL. Data acquisition was started at 5 minutes post-injection. Attenuation-corrected images were evaluated visually. Standardized uptake values (SUV) were calculated of the normal prostate gland and of the prostate tumor tissue. RESULTS: The normal prostate was visualized with a mean SUV of 2.3 (range 1.3-3.2). The primary tumor could be visualized with a mean SUV of 5.0 (range 2.4-9.5). Lymph node metastases >5mm could be identified. Non-specific uptake of CHOL was noticed in the intestines. Little to no radioactivity in the bladder was observed. CONCLUSION: Carbon-11-choline is avidly taken up in prostate cancer, both primary tumor and lymph node metastases, in the virtual absence of urinary radioactivity. These results confirm the early results obtained by others and permit further clinical research on the value of CHOL PET as a metabolic imaging technique in areas where conventional imaging have a limited sensitivity.

Aged↗

Characterization and metabolism of ovine foetal lipids.

1. Total phospholipid concentrations in liver, kidney and brain of the 140-day ovine foetus were only half of those in comparable maternal tissues. 2. Phosphatidylcholine was the predominant phospholipid in all foetal tissues examined. The most striking difference between foetal and maternal tissues in individual phospholipids was in the heart; foetal heart contained more ethanolamine plasmalogen than choline plasmalogen, whereas in adult tissue the concentration of these was reversed. Sphingomyelin content of foetal brain was only one-sixth of that of maternal brain tissue. 3. Oleic acid (18:1) was the predominant acid in the phospholipid extracted from foetal tissues, except in brain where palmitic acid (16:0) was slightly higher. In phospholipids from adult tissues there was a higher proportion of unsaturated fatty acids (linoleic acid, 18:2, and linolenic acid, 18:3) and a correspondingly lower proportion of oleic acid (18:1). The distribution of fatty acids in the neutral lipid fraction of foetal and maternal tissues was very similar; oleic acid (18:1) was generally the principal component. 4. (14)C derived from [U-(14)C]-glucose and [U-(14)C]fructose infused into the foetal circulation in utero was incorporated into the neutral lipids and phospholipids of heart, liver, kidney, brain and adipose tissue. 5. Phospholipid analysis revealed that the specific activity of phosphatidic acid was higher in liver than in other tissues. The specific activity of phosphatidylethanolamine was less than that of phosphatidylcholine in heart, but in other tissues they were about the same. The specific activities of phosphatidylinositol and phosphatidic acid in brain were very similar and were higher than the other components. The specific activity of phosphatidylserine was highest in liver and brown fat. 6. The pattern of incorporation of (14)C derived from [(14)C]glucose and [(14)C]fructose into foetal neutral lipids was similar. Diglyceride accounted for most of the radioactivity in brain, whereas triglyceride had more label in heart, liver, kidney and fat.

Animals↗

A biochemical and morphologic study of myelination and demyelination. II. Lipogenesis in vitro by rat nerves following transection.

Bilateral transection was performed on rat sciatics. At varying intervals after the operation, samples of nerve were taken both distal and proximal to the level of transection, as well as from the tissue which bridged the gap between the stumps. These samples were incubated in Warburg flasks, with glucose and a labelled lipide precursor (acetate or phosphate). The total lipides were then extracted and their radioactivity was measured. Normal rat sciatics served as controls, and the biochemical and histological findings were correlated. In the distal portion undergoing Wallerian degeneration, the lipide content began to fall before any removal of myelin could be detected histologically. It is suggested that there is a period of "non-cellular removal" prior to the physical breakdown of the myelin. Changes in respiration and in lipogenesis from acetate followed a triphasic course, and agreed with the histological findings in that after a period of predominantly passive changes (approximately 1 to 3 days) there follows a period of cellular reaction (4 to 50 days) and a period of atrophy (from 50 days onward). The incorporation of phosphate into the lipides was increased at all stages examined, even as early as 22 hours after section. This increased P(32) incorporation could not be reproduced in nerves allowed to degenerate in vitro. It is suggested that the hypertrophying Schwann cells synthesize some lipide moieties at a considerably faster rate than others. Proximal to the level of transection, lipogenesis from acetate was depressed, for as long as 32 days postoperatively. It appears, therefore, that the maintenance of the myelin sheath is impaired also above the level of transection. In the "union tissue" which developed between the stumps, prior to the appearance of histologically visible myelin, lipogenesis was low; later it rose above levels for normal nerve. This pattern of lipogenesis in regenerating nerve is similar to that found in growing nerves.

Adipogenesis↗

On the mechanism of malonyl-CoA-independent fatty-acid synthesis. Different properties of the mitochondrial chain elongation and enoylCoA reductase in various tissues.

1. NADPH-specific mitochondrial enoyl-CoA reductase can be assayed by a sensitive radioactive test, employing tritium-labelled NADPH, synthesized in a prefixed reaction from D-[1-3H]-glucose via the hexokinase and glucose-6-phosphate dehydrogenase reactions. 2. Liver, kidney cortex, heart muscle, skeletal muscle, brown adipose tissue, brain cortex, and aortic intimal tissue are investigated concerning chain lengths specificity of the chain elongation and the enoyl-CoA reductase. Medium-chain acyl-CoA compounds prove to be the best primers for the chain elongation. Enoyl-CoA reductases still show large incorporation rates with hexadecenoyl-CoA. 3. The differences in the chain lengths specificity of the chain elongation and enoyl-CoA reductase can be explained by the inhibitory effect of long-chain acyl-CoA derivatives on the 3-hydroxyacyl-CoA dehydrogenase. 4. The nucleotide specificity in the different tissues reveals two types of chain elongation: In addition to liver and kidney cortex, mitochondria of brown adipose tissue need NADH + NADPH for optimal chain elongation, whereas heart muscle, skeletal muscle and aortic intimal mitochondria only need NADH. 5. Different physiological roles are proposed for the two types. The "heart type" may be of importance in the conservation of reducing equivalents or acetate units in the anaerobic state, the "liver type" may play a role in the transfer of hydrogen from NADPH to the respiratory chain. In addition, the mitochondrial chain elongation may serve as bypass of the first part of the respiratory chain.

Adipose Tissue, Brown↗

Hexose metabolism in pancreatic islets. Ca(2+)-dependent activation of the glycerol phosphate shuttle by nutrient secretagogues.

A method is proposed for the measurement of the flux through the glycerol phosphate shuttle in pancreatic islets. Such a flux is taken as the ratio between the production of 3HOH and the specific radioactivity of L-[2-3H]glycerophosphate in islets exposed to [2-3H]glycerol. D-Glucose and non-glucidic nutrient secretagogues, such as 2-ketoisocaproate and 2-aminobicyclo[2,2,1]heptane-2-carboxylate, stimulate, in a Ca(2+)-dependent manner, circulation in the glycerol phosphate shuttle. The shuttle flux is commensurate with the fraction of pyruvate generation which is not coupled with L-lactate production. These findings support the view that a rise in D-glucose concentration leads to activation of the FAD-linked mitochondrial glycerophosphate dehydrogenase through an increase in cytosolic Ca2+ concentration.

Animals↗

Transient toxicity of 2-deoxy-2-[18F]fluoro-D-glucose in mammalian cells: concise communication.

The kinetics of uptake and toxicity of the positron emitter F-18 have been examined in a cultured cell line. 2-Deoxy-2[18F]fluoro-D-glucose (18FDG) concentrated rapidly within Chinese hamster V79 cells, and the uptake was linear with the extracellular radioactive concentrations. Whereas 18FDG synthesized 2 hr before the incubation did not appear to be toxic, that synthesized 5 hr previously was highly toxic. Toxicity was transient and independent of both the extracellular/intracellular radioactive concentration and the energy released from the decay of fluorine-18. Similarly synthesized nonradioactive FDG and Na 18F were not toxic under comparable experimental conditions. We conclude that this transient toxicity is due to an unidentified chemical species that is cytocidal following intracellular localization. These toxic levels are not likely to be achieved in the clinical use of 18FDG due to dilution factors that are orders of magnitude greater than those used in these in vitro studies.

Animals↗

Structures of the asparagine-linked sugar chain of glucose transporter from human erythrocytes.

The asparagine-linked sugar chain of glucose transporter from human erythrocytes was quantitatively released as oligosaccharides from the polypeptide backbone by hydrazinolysis. They were converted to radioactive oligosaccharides by NaB3H4 reduction after N-acetylation and fractionated by anion-exchange column chromatography and Bio-Gel P-4 column chromatography after sialidase treatment. Structural study of each oligosaccharide by exo- and endoglycosidase digestion and methylation analysis indicated that the glycoprotein contains a high-mannose-type oligosaccharide, Man9.GlcNAc.GlcNAc, and biantennary complex-type oligosaccharides with Man alpha 1----6(+/- GlcNAc beta 1----4)(Man alpha 1----3) Man beta beta 1----4GlcNAc beta 1----4(+/- Fuc alpha 1----6)GlcNAc as their cores and the poly-N-acetyllactosamine composed of about 16 N-acetyllactosaminyl units as their outer chains. These structural features of the sugar moiety of glucose transporter are quite different from those of two major intrinsic glycoproteins of human erythrocytes, glycophorin A and band 3.

Amino Sugars↗