Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The insulin-like growth-factor-II/mannose-6-phosphate (IGF-II/Man6P) receptor binds two classes of ligands, insulin-like growth factors and lysosomal enzymes. We have examined the ability of the lysosomal enzyme, beta-galactosidase, to modulate the binding of 125I-IGF-II to the receptor. beta-Galactosidase purified from bovine testis was fractionated on a DEAF-Sephacel ion-exchange column. Column fractions were assayed for enzymatic activity and for ability to inhibit the binding of 125I-IGF-II to the IGF-II/Man6P receptor. Enzyme fractions eluting at higher NaCl concentrations which had previously been shown to exhibit greater uptake by cells in culture, exhibited greater potency in inhibiting the binding of 125I-IGF-II to the receptor. A pool of these fractions from the DEAE-Sephacel column inhibited 125I-IGF-II binding to pure receptor by 80% with the concentration required for half-maximal inhibition being 25 nM. The inhibition of binding by beta-galactosidase was completely blocked by simultaneous incubation with Man6P. Inhibition of the enzymatic activity of beta-galactosidase with D-galactonic acid gamma-lactone did not affect the ability of beta-galactosidase to inhibit the binding of 125I-IGF-II to the receptor. Scatchard analysis of IGF-II binding to pure receptor in the presence and absence of beta-galactosidase showed that beta-galactosidase decreased the binding affinity for IGF-II (Kd 0.26 nM versus 1.0 nM in the presence of 57 nM beta-galactosidase). We confirmed the observations of others that Man6P alone actually increases the binding of 125I-IGF-II to the IGF-II/Man6P receptor, but we found that this phenomenon was dependent upon the method of preparation of the IGF-II/Man6P receptor. Microsomal membrane preparations, solubilized membranes, and receptors purified on an IGF-II-Sepharose column all exhibited stimulation of 125I-IGF-II binding by Man6P, whereas receptors purified on lysosomal enzyme affinity columns showed little or no stimulation of 125I-IGF-II binding by Man6P. We conclude that beta-galactosidase decreases the binding affinity of the IGF-II/Man-6-P receptor for IGF-II by binding with high affinity to the Man6P-recognition site.
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PMID:Beta-galactosidase decreases the binding affinity of the insulin-like-growth-factor-II/mannose-6-phosphate receptor for insulin-like-growth-factor II. 216 34

The gene for a secreted 130-kilodalton beta-galactosidase from "Streptomyces lividans" has been cloned, its promoter, signal sequence, and amino terminal region have been localized, and their nucleotide sequence has been determined. The signal sequence extends over 56 amino acids and shows the characteristic-features of signal sequences, including a hydrophilic amino terminus followed by a hydrophobic core near the signal cleavage site. The secretion of beta-galactosidase depends on the presence of the signal sequence. beta-Galactosidase is the major protein in culture supernatants and extracts of strains expressing the cloned beta-galactosidase gene and represents a valuable tool in the study of protein secretion in Streptomyces spp.
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PMID:Characterization of the promoter, signal sequence, and amino terminus of a secreted beta-galactosidase from "Streptomyces lividans". 244 41

Effects of alpha-galactosidase (from green coffee beans) digestion on lectin staining were examined in formalin-fixed, paraffin-embedded human pancreatic tissues from individuals of blood-group B and AB. Digestion with the enzyme resulted in almost complete loss of Griffonia simplicifolia agglutinin I-B4 (GSAI-B4) staining in the acinar cells with concomitant appearance of Ulex europaeus agglutinin-I(UEA-I) staining in the corresponding cells. In addition, reactivity with soybean agglutinin(SBA) was also imparted by the enzyme digestion in GSAI-B4 positive acinar cells. beta-Galactosidase digestion following alpha-galactosidase digestion neither reduced the reactivity with SBA nor induced the reactivity with Griffonia simplicifolia agglutinin-II(GSA-II) in GSAI-B4 positive cells, while in UEA-I positive cells, both reduction of SBA reactivity and appearance of GSA-II reactivity occurred after simple beta-galactosidase digestion as well as sequential digestion with alpha- and beta-galactosidase. However, when alpha-L-fucosidase digestion procedure was inserted between alpha- and beta-galactosidase digestion, UEA-I staining imparted by alpha-galactosidase digestion was markedly decreased in intensity and GSA-II reactivity was appeared in GSAI-B4 positive acinar cells. Furthermore, after sequential digestion with alpha-galactosidase and fucosidase, reactivity with peanut agglutinin(PNA) was revealed in GSAI-B4 positive acinar cells as well as UEA-I positive cells in secretors. In non-secretors, strong PNA staining was usually observed in the acinar cells throughout the glands without enzyme digestion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of alpha-galactosidase digestion on lectin staining in human pancreas. 245 77

Expression of beta-galactosidase in transcriptional fusions with the pps gene (encoding phosphoenolpyruvate [PEP] synthase), the aceBAK operon (encoding malate synthase, isocitrate lyase, and isocitrate dehydrogenase kinase, respectively), and the phs operon (encoding either thiosulfate reductase or a regulatory protein controlling its expression) was studied in Salmonella typhimurium. beta-Galactosidase synthesis in these strains was repressible either by growth in the presence of glucose or by the presence of a fruR mutation, which resulted in the constitutive expression of the fructose (fru) regulon. Five enzymes of gluconeogenesis (PEP synthase, PEP carboxykinase, isocitrate lyase, malate synthase, and fructose-1,6-diphosphatase) were shown to be repressed either by growth in the presence of glucose or the fruR mutation, while the glycolytic enzymes, enzyme I and enzymes II of the phosphotransferase system as well as phosphofructokinase, were induced either by growth in the presence of glucose or the fruR mutation. Overexpression of the cloned fru regulon genes (not including fruR) resulted in parallel repression of representative gluconeogenic, Krebs cycle, and glyoxylate shunt enzymes. Studies with temperature-sensitive mutants of S. typhimurium which synthesized heat-labile IIIFru proteins provided evidence that this protein plays a role in the regulation of gluconeogenic substrate utilization. Other mutant analyses revealed a complex relationship between fru gene expression and the expression of genes encoding gluconeogenic enzymes. Taken together, the results suggest that a number of genes encoding catabolic, biosynthetic, and amphibolic enzymes in enteric bacteria are transcriptionally regulated by a complex catabolite repression/activation mechanism which may involve enzyme IIIFru of the phosphotransferase system as one component of the regulatory system.
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PMID:Altered transcriptional patterns affecting several metabolic pathways in strains of Salmonella typhimurium which overexpress the fructose regulon. 249 6

In the present review the authors analyze factors influencing sensitivity of the enzyme immunoassay (EIA). beta-Galactosidase from E. coli was chosen as a marker enzyme. Physico-chemical properties of the enzyme, detection methods and various ways of obtaining chemical conjugates with antigens and antibodies are discussed. Some examples of using beta-galactosidase as a label in homogeneous and heterogeneous EIA are given which enables different compounds to be analyzed with a high sensitivity. New approaches employing gene engineering for constructing "fusions" between beta-galactosidase and antigens (alternative to chemical conjugates) are discussed that can be used in the near future.
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PMID:[Beta-galactosidase from E. coli as a marker in immunoenzyme analysis]. 249 78

The genome of the cyanobacterium Synechococcus sp. strain PCC 7942 contains three psbA genes encoding two forms of the D1 protein: form I, the product of psbAI, differs from form II, the product of both psbAII and psbAIII, at 25 of 360 residues. D1 is essential for photosynthesis as a core component of the photosystem II reaction center. Translational gene fusions between each of the Synechococcus psbA genes and the Escherichia coli lacZ gene were inserted into the chromosome of wild-type Synechococcus sp. at the respective psbA loci to serve as in vivo reporters of psbA expression. beta-Galactosidase activities indicated differential expression of the psbA-lacZ gene fusions related to light availability. Expression of psbAI was 500-fold greater than expression of psbAII and 50-fold greater than psbAIII under similar conditions. As light intensity decreased from 600 microE.m-2.s-1 to 2 microE.m-2.s-1, expression of the psbAI reporter increased eightfold while expression of the psbAII and psbAIII reporters decreased 10-fold, suggesting differential production of the two forms of D1 in photosystem II in response to light availability. Relative levels of psbA-lacZ fusion transcripts directly reflected beta-galactosidase activities in the transformants, although the fusion transcripts were less stable than native psbA messages.
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PMID:Differential expression of members of a cyanobacterial psbA gene family in response to light. 250 Apr 19

Although lysosomal enzyme activities are known to vary in response to numerous physiological and pharmacological stimuli, the relationship between lysosomal enzyme activity and enzyme concentration has not been systematically studied. Therefore we developed radioimmunoassays for two lysosomal glycosidases in order to determine lysosomal enzyme concentration. beta-Galactosidase and beta-glucuronidase were purified from rat liver 2780-fold and 1280-fold respectively, by using differential centrifugation, affinity chromatography, ion-exchange chromatography and molecular-sieve chromatography. Polyclonal antibodies to these enzymes were raised in rabbits, and two radioimmunoassays were established. Antibody specificity was shown by: (i) selective immunoprecipitation of enzyme activity; (ii) identical bands of purified enzyme on SDS/polyacrylamide-gel electrophoresis and immunoelectrophoresis; (iii) single immunoreactive peaks in molecular-sieve chromatography experiments. Sensitivities of the assays were such that 15 ng of beta-galactosidase and 45 ng of beta-glucuronidase decreased the ratio of bound to free radiolabel by 50%; minimal detectable amounts of immunoreactive enzymes were 2 ng and 10 ng respectively. The assays were initially used to assess the effects of physiological perturbations (i.e. fasting and age) on enzyme concentrations in rat liver; these experiments showed that changes in enzyme concentrations do not always correlate with changes in enzyme activities. This represents the first report of radioimmunoassays for lysosomal glycosidases. The results suggest that these radioimmunoassays provide useful technology for the study of regulatory control mechanisms of the concentrations of lysosomal glycosidases in mammalian tissues.
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PMID:Purification and immunological quantification of rat liver lysosomal glycosidases. 251 4

During latent infection by herpes simplex virus (HSV), an abundant latency-associated transcript (LAT) that is antisense to a predominant viral alpha gene (ICP0) is found localized in the nucleus of sensory neurons. We disrupted both copies of the LAT gene in the HSV-1 genome by insertion of the Escherichia coli lacZ gene under LAT promoter control. The resulting recombinant virus, RH142, does not express any detectable LAT in either latently or productively infected cells, although beta-galactosidase expression is readily detectable in sensory neurons of latently infected mice. Expression was first detectable 3 days postinoculation and continued at approximately the same level for the entire experimental period (56 days). beta-Galactosidase expression was not detectable at any time during RH142 replication in Vero cells. Thus, the kinetics of expression and cell-type specificity of the LAT gene are distinct from other HSV-1 genes that are expressed during productive growth. When latently infected trigeminal ganglia were explanted, RH142 reactivated from latency with the kinetics and an efficiency indistinguishable from the parental wild-type virus. These studies argue against any possible antisense regulatory mechanism of LAT in the regulation of viral gene expression or any role of LAT-encoded protein during the establishment or maintenance of latency in the mouse.
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PMID:Herpes simplex virus latent RNA (LAT) is not required for latent infection in the mouse. 255 49

The lacZ gene of Escherichia coli, coding for beta-galactosidase, is a widely used reporter gene for gene expression studies in microbial and animal systems. To demonstrate that it is also a powerful reporter gene in plants, lacZ was fused to 5' regulatory elements of several genes known to be functional in plant cells. By measuring LacZ activities in transgenic plants containing these gene constructs, we showed that the reporter is correctly monitoring the regulatory properties of the well-characterized promoters fused to lacZ. beta-Galactosidase was assayed directly in plant extracts when they contained high levels of LacZ or, when LacZ was expressed at low level, by separating the endogenous and LacZ activities electrophoretically and detecting the enzymes with a fluorogenic substrate. The most outstanding property of the marker is its amenability to histochemical detection. Due to its stability, LacZ can be fixed in the tissue with glutaraldehyde without loss of activity and detected with high resolution by using XGal. We could reveal expression patterns unnoticed earlier for many of the regulatory elements studied. The chlorophyll a/b binding protein gene, expressed at very high levels in green tissues, is also expressed at a low level in the vascular cylinder of the root. The Agrobacterium T-DNA gene encoding octopine synthase is especially active in the epidermis of the root tip and the TR2' gene was shown to be root specific in the intact plant and stimulated by wounding in the leaf tissue. The TR1' gene, fused to nptII, shows similar characteristics suggesting co-regulation of this tightly linked dual promoter.
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PMID:Gene fusions to lacZ reveal new expression patterns of chimeric genes in transgenic plants. 265 53

Expression of the cloned glnA gene [coding for glutamine synthetase (EC 6.3.1.2)] of Bacillus subtilis was 10-fold higher in an Escherichia coli strain grown under nitrogen-limiting conditions than in the same strain under nitrogen-excess conditions. Mutations in the E. coli glnA, glnB, glnD, glnE, glnF, glnG, and glnL genes had no effect on the observed regulation. To test whether sequences within the B. subtilis DNA (3.2 kilobase pairs) were responsible for the observed regulation, a plasmid carrying a transcriptional fusion of the B. subtilis glnA promoter with E. coli lacZ was constructed. beta-Galactosidase levels coded for by this plasmid were found to be negatively regulated in trans by a plasmid carrying the entire B. subtilis glnA gene. Analysis of various deletion plasmids showed that the 1.4-kilobase-pair region encoding glutamine synthetase was necessary for the observed regulation of beta-galactosidase. Plasmids coding for 67% or more of the glutamine synthetase polypeptide gave at least partial repression, but a plasmid carrying 30% of the structural gene, as well as a plasmid carrying a deletion internal to glnA, gave no repression. DNA downstream from glnA (to within 130 base pairs of the end of the gene) was not required for the observed regulation. These results suggest that the glnA gene of B. subtilis is autoregulated, supporting the model for glnA control proposed by Dean et al. [Dean, D. R., Hoch, J. A. & Aronson, A. I. (1977) J. Bacteriol. 131, 981-987].
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PMID:Regulation of expression from the glnA promoter of Bacillus subtilis requires the glnA gene product. 286 Jun 69


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