SEARCH · Search PubMed

Results for “GALACTOSE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources

PubMed1990

Carbohydrate binding activities of Bradyrhizobium japonicum. II. Isolation and characterization of a galactose-specific lectin.

Extracts of Bradyrhizobium japonicum were fractionated on Sepharose columns covalently derivatized with lactose. Elution of the material that was specifically bound to the affinity column with lactose yielded a protein of Mr approximately 38,000. Isoelectric focusing of this sample yielded two spots with pI values of 6.4 and 6.8. This protein specifically bound to galactose-containing glycoconjugates, but did not bind either to glucose or mannose. Derivatives of galactose at the C-2 position showed much weaker binding; there was an 18-fold difference in the relative binding affinities of galactose versus N-acetyl-D-galactosamine. These results indicate that we have purified a newly identified carbohydrate-binding protein from Bradyrhizobium japonicum, that can exquisitely distinguish galactose from its derivatives at the C-2 position.

Binding, Competitive↗

PubMed1971

Elaboration of the matrix glycoprotein of enamel by the secretory ameloblasts of the rat incisor as revealed by radioautography after galactose- 3 H injection.

The elaboration of enamel matrix glycoprotein was investigated in secretory ameloblasts of incisor teeth in 30-40-g rats. To this end, the distribution of glycoprotein was examined histochemically by the use of phosphotungstic acid at low pH, while the formation of glycoprotein was traced radioautographically in animals sacrificed 2.5-30 min after galactose-(3)H injection. Histochemically, the presence of glycoprotein is observed in ameloblasts as well as in the enamel matrix; in ameloblasts glycoprotein occurs within the Golgi apparatus in amounts increasing from the outer to the inner face of the stacks of saccules, and is concentrated in condensing vacuoles and secretory granules; in the enamel matrix, glycoprotein is observed within linear subunits. Radioautographs at 2.5 min after injection demonstrate the uptake of galactose-(3)H label by Golgi saccules, indicating that galactose-(3)H is incorporated into glycoprotein within this organelle. After 5-10 min, the label collects in the condensing vacuoles and secretory granules of the Golgi region. By 20-30 min, the label appears in the secretory granules of the apical (Tomes') processes, as well as in the enamel matrix (next to the distal end of the apical processes, and at the tips of matrix prongs). In conclusion, galactose contributes to the formation of glycoprotein within the Golgi apparatus. The innermost saccules then distribute the completed glycoprotein to condensing vacuoles, which later evolve into secretory granules. These granules rapidly migrate to the apical processes, where they discharge their glycoprotein content to the developing enamel.

Ameloblasts↗

PubMed2002

Association of galactose-1-phosphate uridyltransferase activity and N314D genotype with the risk of ovarian cancer.

Deficiency in the galactose-1-phosphate uridyltransferase (GALT) enzyme results in accumulation of galactose and its metabolites in the ovary (Am J Epidemiol 1989;130:904-10). Galactose may raise gonadotropin levels, resulting in proliferation of ovarian epithelium. In 1993-1999, the authors conducted a population-based case-control study of ovarian cancer in Hawaii and Los Angeles, California, to examine the hypothesis that reduced GALT activity is associated with an increased risk of ovarian cancer. A total of 239 ovarian cancer cases and 244 population controls were interviewed. A blood sample was collected to measure levels of GALT and to assay for the N314D (A940G) polymorphism of the GALT gene. Covariate-adjusted mean GALT activity was similar between cases (23.8 micro mol per hour/g hemoglobin (Hb)) and controls (23.7 micro mol per hour/g Hb) (p = 0.83). No evidence was found for a dose-response relation between the odds ratios for ovarian cancer and GALT activity or the ratio of lactose intake to GALT activity. The risk associated with the presence of at least one variant Asp314 allele was 0.77 (95% confidence interval: 0.42, 1.41). This study did not support the hypothesis that reduced galactose metabolism is a risk factor for ovarian cancer, although increased GALT activity attenuated the inverse association of oral contraceptive pill use with risk.

Adult↗

PubMed1974

Dilution kinetic studies of yeast populations: in vivo aggregation of galactose utilizing enzymes and positive regulator molecules.

By use of a selective medium containing ethidium bromide, population analyses of yeast galactose long-term adaptation mutants (gal3) in the process of deadaptation in the absence of galactose have been performed. The analysis of diploid strains homozygous for the gal3 locus but heterozygous for different combinations of the other mutant galactose loci, which thus have reduced amounts of the gene products of those loci, have demonstrated that, in addition to the two permease units determined in a previous study, a cell requires one complex of the Leloir pathway enzymes and two complexes specified by the Gal4 locus to be readily induced. From the consideration of these complexes as being aggregated molecules which are diluted out as units (i.e., if such a molecule were a dimer, it would not dissociate into monomers) during cell growth, the in vivo aggregation of these enzymes and the Gal4 gene product could be studied. The data indicate that the function of the Gal4 gene product is to activate a Leloir enzyme complex. It is postulated that the gal3 phenotype is the result of such strains' inability to actively synthesize an endogenous co-inducer which allows wild-type cells to be readily induced upon exposure to galactose.

Carbohydrate Epimerases↗

PubMed1995

CD23 molecule acts as a galactose-binding lectin in the cell aggregation of EBV-transformed human B-cell lines.

Epstein-Barr virus (EBV)-transformed human B-cell lines, L-KT9 and DH3 cells express CD23 antigen, and grow in a mixture of single and aggregated cells. The CD23 molecule has high amino acid sequence homology with C-type lectin and recently we have shown that the solubilized CD23 molecule can really interact with galactose residues on glycoproteins. In this study, therefore, we tested whether CD23 antigen on the cell surface really acts as a galactose-binding lectin in the aggregation of these cells. The EBV-transformed cells (L-KT9) were separated into an aggregated-cell-rich fraction and a single-cell-rich fraction. Aggregated cells disaggregated after removal of galactose by beta-galactosidase treatment, whereas single cells made large aggregation on sialidase treatment, and this aggregation was inhibited in the presence of asialo-fetuin. On the other hand, naturally aggregated cells become single cells with anti-CD23 monoclonal antibody (mAB) as well as the soluble form of CD23, but not with anti-CD21 mAB. In addition, L-KT9 and DH3 cells bound to asialo-fetuin-coupled Sepharose (ASF-Sepharose) and this binding was significantly inhibited by pre-treatment of cells with anti-CD23, but not with anti-CD21 or other anti-adhesion molecules. From these results, we conclude that the naturally aggregated state of EBV-transformed cells occurs mainly through the interaction of CD23 as a lectin molecule and galactose residues as its ligand.

Antibodies, Monoclonal↗

PubMed1998

All pyruvylated galactose in Schizosaccharomyces pombe N-glycans is present in the terminal disaccharide, 4, 6-O-[(R)-(1-carboxyethylidine)]-Galbeta1,3Galalpha1-.

The large N-linked oligosaccharides released from Schizosaccharomyces pombe by endo-beta-N-acetylglucosaminidase H were examined to determine how the negatively chargedpyruvylated galactoses present (Gemmill,T.R., and Trimble,R.B., 1996, J. Biol. Chem ., 271, 25945-25949) were attached to the oligosaccharide chains. Binding of biotinylated human serum amyloid P and peanut agglutinin to native and depyruvylated S.pombe glycoproteins, respectively, indicated that the pyruvylated epitope was likely to be in the beta configuration. Examination by high-field 1H NMR of whole glycans and a disaccharide fragment released from them on partial acid hydrolysis showed that the pyruvylated galactose species was in fact beta1,3-linked to a second galactose, and this occurred an average of five to six times on nominal Gal57Man64GlcNAc N-glycans. The pyruvate-2,(4,6)Gal-beta1,3Gal epitope is chemically similar to acetaldehyde-Galbeta1,3Gal groups found on the glycoproteins from Paramyxovirus-infected bovine kidney cells (Prehm, P., Scheid,A. and Choppin,P.W. ,1979, J. Biol. Chem ., 254, 9669-9677). The 1:1 stoichiometry between pyruvate and beta-linked galactose in these S.pombe glycans indicates that either pyruvate addition to terminal beta1,3Gal is highly efficient or that pyruvylated Gal is transferred en bloc to alpha1,2-linked Gal residues in theN-linked chains. In contradiction to many galactomannan-producing fungi, which add substantial amounts of Gal in the furanose form to their glycoproteins, all detectable Gal in the large S.pombe galactomannans is in the pyranose form, as found in higher eukaryotes. The current work shows that the S.pombe outer chain structure is a poly-alpha1,6Man backbone 2-O-substituted with either Gal or the pyruvylated galactobiose and contains little alpha1,2-linked or 2-O-substituted Man. This is in contrast to the S. cerevisiae outer chain, which is poly-alpha1,6Man substituted with alpha1,2-linked Man sidechains (Ballou,C.E. ,1990, Methods Enzymol , 185, 440-470).

Animals↗

PubMed1999

Enzymically inactive members of the trans-sialidase family from Trypanosoma cruzi display beta-galactose binding activity.

trans-sialidase is a unique sialidase in that, instead of hydrolizing sialic acid, it preferentially transfers the monosaccharide to a terminal beta-galactose in glycoproteins and glycolipids. This enzyme, originally identified in Trypanosoma cruzi, belongs to a large family of proteins. Some members of the family lack the enzymatic activity. No function has been yet assigned to them. In this work, the gene copy number and the possible function of inactive members of the trans -sialidase family was studied. It is shown that genes encoding inactive members are not a few, but rather, are present in the same copy number (60-80 per haploid genome) as those encoding active trans -sialidases. Recombinant inactive proteins were purified and assayed for sialic acid and galactose binding activity in agglutination tests. The enzymatically inactive trans -sialidases were found to agglutinate de-sialylated erythrocytes but not untreated red blood cells. Assays made with mouse and rabbit red blood cells suggest that inactive trans -sialidases bind to beta, rather than alpha, terminal galactoses, the same specificity required by active trans -sialidases. A recombinant molecule that was made enzymatically inactive through a mutation in a single amino acid also retained the galactose binding activity. The binding was competed by lactose and was dependent on conservation of the protein native conformation. Therefore, at least some molecules in the trans -sialidase family that have lost their enzymatic function still retain their Gal-binding properties and might have a function as lectins in the parasite-host interaction.

Amino Acid Sequence↗

PubMed2004

Molecular cloning of two Arabidopsis UDP-galactose transporters by complementation of a deficient Chinese hamster ovary cell line.

Nucleotide-sugar transporters (NSTs) form a family of structurally related transmembrane proteins that transport nucleotide-sugars from the cytoplasm to the endoplasmic reticulum and Golgi lumen. In these organelles, activated sugars are substrates for various glycosyltransferases involved in oligo- and polysaccharide biosynthesis. The Arabidopsis thaliana genome contains more than 40 members of this transporter gene family, of which only a few are functionally characterized. In this study, two Arabidopsis UDP-galactose transporter cDNAs (UDP-GalT1 and UDP-GalT2) are isolated by expression cloning using a Chinese hamster ovary cell line (CHO-Lec8) deficient in UDP-galactose transport. The isolated genes show only 21% identity to each other and very limited sequence identity with human and yeast UDP-galactose transporters and other NSTs. Despite this low overall identity, the two proteins clearly belong to the same gene family. Besides complementing Lec8 cells, the two NSTs are shown to transport exclusively UDP-galactose by an in vitro NST assay. The most homologous proteins with known function are plant transporters that locate in the inner chloroplast membrane and transport triose-phosphate, phosphoenolpyruvate, glucose-6-phosphate, and xylulose 5-phosphate. Also, the latter proteins are members of the same family, which therefore has been named the NST/triose-phosphate transporter family.

Amino Acid Sequence↗

PubMed2006

Two categories of mammalian galactose-binding receptors distinguished by glycan array profiling.

Profiling of the four known galactose-binding receptors in the C-type lectin family has been undertaken in parallel on a glycan array. The results are generally consistent with those of previous assays using various different formats, but they provide a direct comparison of the properties of the four receptors, revealing that they fall into two distinct groups. The major subunit of the rat asialoglycoprotein receptor and the rat Kupffer cell receptor show similar broad preferences for GalNAc-terminated glycans, while the rat macrophage galactose lectin and the human scavenger receptor C-type lectin (SRCL) bind more restricted sets of glycans. Both of these receptors bind to Lewis x-type structures, but the macrophage galactose lectin also interacts strongly with biantennary galactose- and GalNAc-terminated glycans. Although the similar glycan-binding profiles for the asialoglycoprotein receptor and the Kupffer cell receptor might suggest that these receptors are functionally redundant, analysis of fibroblasts transfected with full-length Kupffer cell receptor reveals that they fail to endocytose glycosylated ligand.

Amino Acid Sequence↗

PubMed2000

A mouse model of galactose-induced cataracts.

Galactokinase (GK; EC 2.7.1.6) is the first enzyme in the metabolism of galactose. In humans, GK deficiency results in congenital cataracts due to an accumulation of galactitol within the lens. In an attempt to make a galactosemic animal model, we cloned the mouse GK gene (Glk1) and disrupted it by gene targeting. As expected, galactose was very poorly metabolized in GK-deficient mice. In addition, both galactose and galactitol accumulated in tissues of GK-deficient mice. Surprisingly, the GK-deficient animals did not form cataracts even when fed a high galactose diet. However, the introduction of a human aldose reductase transgene into a GK-deficient background resulted in cataract formation within the first postnatal day. This mouse represents the first mouse model for congenital galactosemic cataract.

Aldehyde Reductase↗

PubMed2003

Prenatal exposure to high galactose adversely affects initial gonadal pool of germ cells in rats.

BACKGROUND: In rats, prenatal exposure to high concentrations of galactose may contribute to a condition that is equivalent to the premature ovarian failure (POF) component of human galactosaemia. We investigated if development of POF under experimental galactosaemia-like conditions was attributed to impaired germ cell migration. METHODS: Pregnant rats were fed pellets supplemented with, or without, 35% galactose from day 3 of conception continuing through parturition. Between days 12-15, embryos from one uterine horn were dissected out. Primordial germ cells (PGC) were histochemically localized and counted on the basis of binding of Dolichos biflorus agglutinin, a lectin specific for terminal N-acetylgalactosamine (GalNAc), to the surface glycoconjugate of the germ cells. The embryos from the other uterine horn were maintained until parturition. Liver activity of uridine diphosphate galactose 4-epimerase, the enzyme involved at multiple steps in the process of synthesis of GalNAc, was assayed in 1-2 day old female pups. RESULTS: The numbers of PGC at the day-specific sites on all days of examination were significantly lower (P </= 0.0003), and liver epimerase activity was significantly (P = 0.000001) reduced in the galactose-exposed group. CONCLUSION: Impaired germ cell migration leading to the development of gonads with deficient initial pools of germ cells may form the causal link between galactosaemia and POF.

Animals↗

PubMed1990

The effect of the progression of vitamin A deficiency on glucose, galactose and mannose incorporation into sugar phosphates and sugar nucleotides in hamster liver.

The incorporation of [2-3H]mannose into dolichyl phosphate mannose and glycoproteins is markedly reduced in livers of vitamin A-deficient hamsters. To determine whether vitamin A deficiency selectively alters the level of mannose incorporation into sugar phosphates and sugar nucleotides, we studied the in vivo incorporation of [2-3H]mannose, [5-3H]glucose, and [4,5-3H]galactose into sugar phosphates and sugar nucleotides. Male hamsters fed either a vitamin A-depleted or a retinoic acid-supplemented (3 micrograms/g) diet were used at 4, 6 and 8 wk of age; the animals were killed at various time points after an intraperitoneal injection of the radiolabeled sugar. A two- to threefold increase in the amount of [2-3H]mannose was found in liver of hamsters fed a vitamin A-depleted diet for 4 wk, resulting in enhanced incorporation into mannosyl-phosphate and guanosine diphosphate (GDP) mannose. As deficiency progressed, there was a smaller increase in [2-3H]mannose and a significant decrease in [3H]mannose-phosphate and GDP-[3H]mannose, suggesting a decreased mannose kinase activity. [5-3H]Glucose-labeled livers showed no difference in the total uptake of the label or its incorporation into uridine diphosphate glucose and galactose-phosphate during the 8-wk study. However, the synthesis of glucosyl-phosphate was reduced by 50 to 90% at 6 and 8 wk of deficiency, suggesting an impaired gluco-kinase activity. In hamsters injected with [4,5-3H]galactose only [3H]glucose was found within 5 min in the free sugar fraction. In contrast, as much as 70% of the label in the sugar phosphate and sugar nucleotide fraction remained as [3H]galactose even at 60 min. These effects on sugar, sugar phosphate and sugar nucleotide formation in part may explain the effects of vitamin A deficiency on glycoconjugate biosynthesis.

Animals↗

PubMed2001

TX14(A), a prosaposin-derived peptide, reverses established nerve disorders in streptozotocin-diabetic rats and prevents them in galactose-fed rats.

Recently, TX14(A), a prosaposin-derived neurotrophic peptide, was shown to prevent both large and small fiber deficits in streptozotocin diabetes. Here, the efficacy of TX14(A) in reversing established nerve conduction disorders in streptozotocin diabetes, a model of insulin deficiency, and preventing them in galactose feeding, an insulin-replete model of polyol pathway flux, was investigated. Following streptozotocin injection (50 mg/kg ip), TX14(A) treatment (1 mg/kg ip thrice weekly) was initiated in half of the animals. After 8 wk, treatment was begun in half of the untreated animals and discontinued in half of the treated animals, and the experiment continued for 6 wk. TX14(A) reversed established motor and sensory nerve conduction deficits in streptozotocin-diabetic rats and the impact of previous treatment was still evident 3 wk after withdrawal. With the onset of 40% galactose feeding, the same dose of TX14(A) was given to half of the control and half of the galactose-fed animals for 16 wk. TX14(A) was without effect in control animals but it attenuated motor and sensory nerve conduction deficits in galactose-fed rats, an effect associated with amelioration of axonal dwindling in the sciatic nerve. These observations extend the therapeutic utility of TX14(A) and highlight its potential in treating established diabetic neuropathy.

Animals↗

PubMed1997

Expression of the human UDP-galactose transporter in the Golgi membranes of murine Had-1 cells that lack the endogenous transporter.

In our previous study, we demonstrated that UDP-galactose transporter cDNAs (hUGT1 and hUGT2) were able to complement the genetic defect of murine Had-1 cells that were deficient in the UDP-galactose transporter, and that the microsomal vesicles isolated from Had-1-transformants, which were obtained through transfection with these cDNAs, had recovered the ability to uptake UDP-galactose [Ishida, N. et al. (1996) J. Biochem. 120, 1074-1078]. In this report, we describe the preparation of peptide antibodies that recognize the hUGT isozymes, and the detection of hUGT proteins expressed in the transformants. The occurrence of the endogenous hUGT1 protein in HeLa cells was also detected. Using the hUGT1-specific antibodies, the subcellular localization of hUGT1 in the Golgi membrane was demonstrated by immunofluorescence microscopy and subcellular fractionation. These studies led us to develop a simple procedure, based on Percoll density gradient centrifugation, for preparing functional Golgi vesicles from the hUGT1-transformed Had-1 cells, that will facilitate future biochemical analyses of the UDP-galactose transporter for the elucidation of its structure-function relationship.

Amino Acid Sequence↗

PubMed1991

Galactose inhibits auxin-induced growth of Avena coleoptiles by two mechanisms.

Galactose inhibits auxin-induced growth of Avena coleoptiles by at least two mechanisms. First, it inhibits auxin-induced H(+)-excretion needed for the initiation of rapid elongation. Galactose cannot be doing so by directly interfering with the ATPase since fusicoccin-induced H(+)-excretion is not affected. Secondly, galactose inhibits long-term auxin-induced growth, even in an acidic (pH 4.5) solution. This may be due to an inhibition of cell wall synthesis. However, galactose does not reduce the capacity of walls to be loosened by H+, given exogenously or excreted in response to fusicoccin.

Avena↗

PubMedDate not supplied

Diagnosis of congenital glucose-galactose malabsorption by measuring sugar- and amino acid-evoked potential differences in jejunum in vivo.

A girl who was clinically suspected of having congenital glucose-galactose malabsorption was investigated for sugar- and amino acid-evoked potential differences in the jejunum in vivo using a jejunal perfusion technique. She was fed an ordinary diet without suffering diarrhea at the time (at age 2) of this study. Her nutritional condition and development were normal. The disaccharidase activities of a biopsy specimen of the jejunal mucosa, which were assayed at 1 year of age when she was not having diarrhea, were normal. Jejunal perfusion of 100-mM solutions of D-glucose or D-maltose evoked no significant change in the electrical potential difference. On the other hand, 100 mM of L-glycine or L-leucine solution evoked a normal increase of the lumen negative potential difference (4.4 mV and 3.6 mV, respectively). Therefore, the patient was diagnosed as having congenital glucose-galactose malabsorption due to a defect of Na-dependent glucose-galactose active transport. These findings indicate that the measurement of sugar- and amino acid-evoked potential differences is a simple and reliable method for the diagnosis of congenital glucose-galactose malabsorption.

Amino Acids↗

PubMed1999

Evaluation of ammonia and lidocaine clearance, and galactose elimination capacity of xenoperfused pig livers using a pharmacokinetic analysis.

BACKGROUND: We introduced the pharmacokinetic method into the functional evaluation of xenogeneic extracorporeal liver perfusion as an artificial liver assist device, and examined the influence of xenogeneic humoral injury on the metabolic function of xenoperfused pig livers. METHODS: Isolated pig livers were perfused with fresh porcine blood (group 1; n=5) or fresh human blood (group 2; n=5) for 9 hr. Clearance (CL) of ammonia and lidocaine, and galactose elimination capacity (Vmax) were determined at three points during the perfusion using a one-compartment pharmacokinetic model. RESULTS: Concentrations of ammonia and lidocaine decreased exponentially and those of galactose decreased linearly after a bolus injection in both groups. A one-compartment model provided satisfactory curve fittings for these test substances. No decreases of ammonia CL, lidocaine CL, or galactose Vmax were observed until 9 hr in either group. No differences were observed between the two groups with respect to these metabolic functions. In group 1, only slight interlobular edema was observed at 9 hr. In group 2, membrane attack complex was diffusely deposited at 3 hr and severe interlobular damage was histologically observed at 9 hr, although hepatocellular damage was minimal even at 9 hr. Alpha glutathione S-transferase and mitochondrial aspartate aminotransferase were comparable between the two groups. CONCLUSIONS: Pharmacokinetic analysis allowed the evaluation of ammonia CL, lidocaine CL, and galactose Vmax of the perfused pig livers. Despite xenogeneic humoral injuries, the xenoperfused livers maintained these metabolic functions at the same levels as the alloperfused livers for 9 hr.

Ammonia↗

PubMed2005

Increased levels of galactose-deficient IgG in sera of HIV-1-infected individuals.

BACKGROUND: The IgG from sera of patients with chronic inflammatory diseases of autoimmune character or some chronic microbial infections is frequently deficient in galactose on N-linked glycans. However, this phenomenon has not been investigated at length in human viral infections. OBJECTIVES: To evaluate the glycosylation of serum IgG in HIV-1-positive patients. METHODS: Psathyrella velutina lectin was used in enzyme-linked immunosorbent and Western blot assays to determine glycosylation. In addition, gas-liquid chromatography and mass spectrometry were utilized to confirm the galactose deficiency observed in the lectin-binding assays. RESULTS: HIV-1-infected individuals had significantly higher levels of galactose-deficient IgG than healthy controls. In fact, the galactose deficiency of the N-linked glycans observed in other diseases was even more profound in HIV-1 infection. This deficiency was primarily restricted to IgG when total serum glycoproteins were evaluated and IgG1 was the subclass most affected in all patients. Also, a significant increase in lectin binding was observed on IgG2 and IgG4 from HIV-1-positive females compared with HIV-1-negative females. CONCLUSIONS: Identification of deficient galactosylation of serum IgG from HIV-1-infected patients extended the spectrum of diseases in which this phenomenon has been observed. In addition, the results suggest yet another aspect of immune dysfunction as a result of HIV-1 infection.

Adult↗