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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The glucose analogue, 2-deoxy-D-glucose, was used to characterise the glucose transport system in Crithidia luciliae choanomastigotes. Uptake was temperature dependent with a Q10 of 2, and saturable with a Km of 0.22 mM and Vmax of 5.5 nmol min-1 (mg protein)-1 at 23 degrees C. Preloaded cells showed rapid exchange of intracellular 2-deoxy-D-glucose when incubated with extracellular D-glucose or 2-deoxy-D-glucose but little exchange with L-glucose. The substrate specificity of the uptake was studied using a number of D-glucose analogues. 6-Deoxy-D-glucose, 3-fluoro-3-deoxy-D-glucose and 4-fluoro-4-deoxy-D-glucose all competed for the transporter and had significant inhibitory effects on 2-deoxy-D-glucose transport. In contrast, 1-thio-beta-D-glucose, trehalose, 3-O-methyl-D-glucose, arginine, thymidine, L-sorbose and L-glucose were not inhibitory. The results imply the existence of a glucose transporter. The transport was blocked by a number of inhibitors and ionophores, including fluoride, azide, cyanide, dinitrophenol, valinomycin and nigericin. Overall, the uptake, exchange and efflux of 2-deoxy-D-glucose is consistent with transport via facilitated diffusion.
Mol Biochem Parasitol 1992 Nov
PMID:Glucose transport in Crithidia luciliae. 147 88

An acidic glycoconjugate could be extracted from a delipidated residue fraction of [3H]galactose, [3H]mannose or [32P]orthophosphate metabolically labeled Entamoeba histolytica with water/ethanol/diethylether/pyridine/NH4OH (15:15:5:1:0.017). The radioactively labeled glycoconjugate comprised 50-55% of the total [3H]galactose label incorporated into macromolecules. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the radiolabeled glycoconjugate showed two diffuse smears centering around 110 kDa and 45 kDa. Similar profiles were observed for both [3H]galactose- and [32P]orthophosphate-labeled glycoconjugate. No such bands were visible in [35S]methionine-labeled material. The hydrophobic nature of this glycoconjugate was inferred from its chromatographic behavior on phenyl-Sepharose. The molecule was rendered hydrophilic after digestion with phosphatidylinositol-specific phospholipase C. It was also sensitive to deamination by nitrous acid. Mild acid hydrolysis led to its fragmentation into smaller molecules as revealed by Sepharose 4B chromatography. Paper chromatographic analysis of the depolymerized [3H]galactose- and [3H]mannose-labeled fragments revealed that each was sensitive to alkaline phosphatase. The major dephosphorylated fragment migrated as an apparent galactose and mannose containing disaccharide which migrated identically to the Gal beta 1-4Man disaccharide derived from the lipophosphoglycan of Leishmania donovani. The above data support the existence of a major acidic glycoconjugate in E. histolytica bearing striking structural similarities to the lipophosphoglycan of Leishmania.
Mol Biochem Parasitol 1992 Nov
PMID:Identification and partial characterization of a lipophosphoglycan from a pathogenic strain of Entamoeba histolytica. 147 94

The marine blood clam species Anadara granosa (L) belong to arcidae, a family with some extraordinary haematological features. The plasma of this species exhibited strong haemagglutinating activities, from which a galactosyl binding lectin, Anadarin P, was purified in a single step affinity chromatography using Sepharose 4B-asialofetuin as an affinity matrix. The purified lectin, eluted with lactose, was found to be homogeneous by alkaline polyacrylamide disc gels, gel-filtration and isoelectric focusing. Native M(r) of the lectin was 130,000 having a PI value of 6.82 and was composed of two subunits of M(r) 17,000 and M(r) 16,000 which were noncovalently bound. The lectin was remarkably thermostable; the agglutinating titre remained unchanged over a wide range of pH (from 5 to 10) but increased with neuraminidase treated rabbit erythrocytes. Anadarin P combining site has been proposed to be small pocket-like structure which recognised only C-3 and C-4 hydroxyl groups of D-galactose. Presence of bulky groups at C-2 and C-6 exert strong steric hindrance as L-arabinose, 2-deoxy-D-galactose and D-xylose are better inhibitors than D-galactose. The lectin fails to differentiate methyl substituted galactosides as both alpha- and beta- methyl galactosides are equally active; but in case of substituted phenyl glycosides, the lectin shows different affinity towards alpha and beta anomers. The avidity of the lectin to bind the aromatic aglycons of galactosides suggests the presence of a hydrophobic region in the combining site. Interactions with some disaccharides indicate the presence of an extended area near the monosaccharide binding site.
Mol Cell Biochem 1992 Nov 04
PMID:A novel galactosyl-binding lectin from the plasma of the blood clam, Anadara granosa (L) and a study of its combining site. 148 Jan 60

Human respiratory mucin glycoproteins from patients with cystic fibrosis were purified and oligosaccharide chains were released by treatment with alkaline borohydride. A neutral oligosaccharide alditol fraction was isolated from mucin obtained from a patient with A blood group determinant by chromatography on DEAE-cellulose and individual oligosaccharide chains were then isolated by gel filtration on BioGel P-6 columns and high performance liquid chromatography with gradient and isocratic solvent systems. The structures of the purified oligosaccharides were determined by methylation analysis, sequential glycosidase digestion and 'H-NMR spectroscopy. The amount of each chain was determined by compositional analysis. A wide array of discrete branched oligosaccharide structures that contain from 3 to 22 sugar residues were found. Many of the oligosaccharides are related and appear to be precursors of larger chains. The predominant branched oligosaccharides which accumulate contain terminal blood group H (Fuc alpha 2Ga1 beta 4) or blood group A (Fuc alpha 2(Ga1NAc alpha 3) (Ga1 beta 4) determinants which stop further branching and chain elongation. The elongation of oligosaccharide chains in respiratory mucins occurs on the beta 3-linked G1cNAc at branch points, whereas the beta 6-linked G1cNAc residue ultimately forms short side chains with a Fuc alpha 2(Ga1NAc alpha 3) Ga1 beta 4 G1cNAc beta 6 structure in individuals with A blood group determinant. The results obtained in the current studies further suggest that even higher molecular weight oligosaccharide chains with analogous branched structures are present in some human respiratory mucin glycoproteins. Increasing numbers of the repeating sequence shown in the oligosaccharide below is present in the higher molecular weight chains. [formula: see text] This data in conjunction with our earlier observations on the extensive branching of these oligosaccharide chains helps to define and explain the enormous range of oligosaccharide structures found in human and swine respiratory mucin glycoproteins. Comparison of the relative concentrations of each oligosaccharide chain suggest that these oligosaccharides represent variations of a common branched core structure which may be terminated by the addition of alpha 2-linked fucose to the beta 3/4 linked galactose residue at each branch point. These chains accumulate and are found in the highest concentrations in these respiratory mucins.
Mol Cell Biochem 1992 Dec 02
PMID:Quantitation and structures of oligosaccharide chains in human trachea mucin glycoproteins. 148 58

It is well established that the LH/CG receptor expressed in gonadal cells is an 85- to 92-kilodalton (kDa) glycoprotein. Additionally, however, a number of reports have noted the existence of other putative receptor species, but few attempts have been made to characterize these variant receptor species. A cell line [293L(wt1)] had previously been isolated which expresses large numbers of high affinity cell surface LH/CG receptors. Visualization of the LH/CG receptor species expressed in these cells and in rat luteal cells using ligand blots revealed 85- and 90-kDa LH/CG receptors, respectively, while immunoblots revealed another 68-kDa glycoprotein receptor in both cell types. The presence of both the 85- and 68-kDa receptor species was confirmed using immunoprecipitation and affinity purification of metabolically labeled 293L(wt1) cells. Enzymatic deglycosylations established that the 85-kDa receptor is a sialoprotein, while the 68-kDa species contains exposed high mannose residues. Protease digestion before LH/CG receptor immunoprecipitations localized the 85-kDa receptor on the plasma membrane, while the 68-kDa receptor was shown to be located intracellularly. Pulse-chase experiments were then used to positively establish that the 68-kDa receptor protein is actually a precursor of the 85-kDa LH/CG receptor species.
Mol Endocrinol 1992 Dec
PMID:Identification and characterization of a luteinizing hormone/chorionic gonadotropin (LH/CG) receptor precursor in a human kidney cell line stably transfected with the rat luteal LH/CG receptor complementary DNA. 149 99

A soluble mannose binding protein (MBP), obtained from rabbit serum, was found to inhibit phagocytosis of Candida albicans by bone marrow derived, cultured murine macrophages. During in vitro incubation of yeast with lymphocyte-free macrophage populations uptake of the yeast was significantly reduced at MBP concentrations of 5 micrograms/ml. A similar reduction in yeast phagocytosis was produced by dextrose, d-fucose, l-fucose, d-mannose and alpha-methyl-d-mannoside but required saccharide concentrations of 25-50 mg/ml. Inhibition of phagocytosis of the yeast also resulted from pretreatment of either the macrophages or the yeasts with MBP followed by washing. As expected, the addition of mannan to the assay medium blocked the inhibitory effect of MBP for uptake of C. albicans. These findings suggest that both cell bound and soluble mannose receptors may be important modulators of macrophage-Candida interactions.
Cell Mol Biol 1992 Jul
PMID:The effect of a mannose binding protein on macrophage interactions with Candida albicans. 149 40

The present study describes the phenomenon of calciphylaxis, rapid calcification due to treatment with sensitizer dihydrotachysterol (DHT) and challenging agent 5-hydroxytryptamine (5-HT) in the rat submandibular gland (SMG) in terms of light and electron microscopy, and histochemistry. For biophysical analysis of the calcified bodies, X-ray microanalysis (XMA) and X-ray powdered diffraction methods were used. The calcified lesions in the salivary glands were histologically divided into 3 types: type 1, calcification of basal membranes in duct-like structures; type 2, granular calcified materials with remarkable necrotic changes in cell, containing 3 kinds of small vesicular structures observed in electron microscopy; and type 3, von Kossa's positive structures containing needle-like crystalline and electron-dense amorphous materials. Con A and UEA-1 lectin staining reactions were strong in the type 1 and 2 lesions. These findings suggest that the calcification matrix may contain mannose, fucose and glucose. The X-ray microanalysis of calcified materials revealed the magnesium whitelockite pattern, the type 3 displayed high quantities of Ca, P, and Mg ions comparing with the type 1 and 2, and the X-ray diffraction showed the hydroxyapatite pattern. We suggest that the above changes may be categorized as dystrophic calcification due to necrotic alterations brought about by the hypercalcaemic condition.
Cell Mol Biol 1992 Jul
PMID:Experimental calcification in rat submandibular gland. 149 41

Promastigotes from late log phase and 3-day stationary phase cultures of Leishmania donovani were collected, washed in buffer, and the cell pellet was treated with boiling KOH. A putative carbohydrate storage material was then precipitated and washed in ethanol/LiBr. This material did not liberate glucose when treated with amyloglucosidase, indicating that it was not glycogen. Acid hydrolysis released a hexose which was identified as mannose by several criteria. Considerably more of this mannan-like carbohydrate is present in cells from 3-day stationary phase than from late log phase cultures, consistent with the ability of 3-day stationary phase cells to survive in non-nutrient buffer and maintain oxygen consumption for longer than log phase cells. The amount of this mannan-like compound decreased by over 50% during a 3-h incubation in buffer of cells from 3-day stationary phase cultures. The presence of glucose during the incubation prevented the utilization of this carbohydrate, consistent with the possibility that it serves as an energy reserve.
Mol Biochem Parasitol 1992 Jul
PMID:Utilization of a carbohydrate reserve comprised primarily of mannose by Leishmania donovani. 150 39

The beta-anomer of glucose relative to the alpha-anomer was more rapidly metabolized into lactate by rat erythrocytes at 37 degrees C (beta/alpha ratio = ca. 1.3): the amounts of alpha- and beta-D-glucose metabolized into lactate during 3 min were 0.21 and 0.27 mumol/gHb, respectively. Also, the transport of beta-D-glucose into erythrocytes was more rapid than that of alpha-D-glucose: the amounts of alpha- and beta-D-glucose transported into erythrocytes during 3 min were approximately 3.5 and 5.0 mumol/gHb, respectively. Glucose phosphorylation by rat erythrocyte hexokinase (i.e., a possible rate-limiting step in glycolysis) occurred at higher velocities with the beta-anomer than with the alpha-anomer (beta/alpha ratio = 1.28). The Km value of hexokinase for either anomer of glucose was 53 microM. The glucose concentrations in erythrocytes incubated with alpha- and beta-D-glucose reached about 1 mM in 1 min, indicating that hexokinase is almost completely saturated with glucose within less than 1 min. The results suggest that glucose phosphorylation and glucose transport are major and minor determinants, respectively, for the anomeric preference of glucose utilization in rat erythrocytes.
Mol Cell Biochem 1992 May 13
PMID:Anomeric preference of glucose utilization in rat erythrocytes. 151 31

It is well established that normal patterns of epithelial cell proliferation and metabolism, and of fiber cell differentiation and maturation are essential for the maintenance of transparency in the ocular lens. Several factors, including exposure to high levels of sugars, have been known to result in the compromise of lens transparency. For example, initiation of lens cell damage by galactose induces lens epithelial cells to proliferate. Elevated levels of c-myc mRNA have usually been correlated with rapid cell growth and increased entry of cells into the S phase. Therefore, changes in c-myc mRNA levels may provide an early indication of the stimulation of lens epithelial cells to proliferate and differentiate, which has been postulated to be an early and important event in response to lens cell injury by galactose. By Northern blot hybridization analysis we quantitated c-myc mRNA levels in the lens capsule epithelia of rats (1) exposed to galactose, and (2) undergoing a partial recovery from the galactose-induced cell damage. At the onset of lens cell damage, we find c-myc mRNA to elevate to 6-fold by 24 hr, and by 48 hr decreases to about 3-fold the normal levels. During recovery, c-myc mRNA continues to be expressed at high levels approaching a 10-fold increase by day 12, then decreasing to levels of about 8-fold the control by day 30. The 24 h transitory elevation in c-myc mRNA in lens epithelial cells is in accord with our previous observations on the 24 h increase in MP26, gamma crystallin and aldose reductase mRNAs following a high influx of galactose. Therefore, the elevation in c-myc mRNA as well suggest that galactose appears to cause lens cells to undergo an early transitory period of gene induction following the exposure of lens cells to galactose.
Mol Cell Biochem 1992 May 13
PMID:Expression of c-myc protooncogene in rat lens cells during development, maturation and reversal of galactose cataracts. 151 36


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