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

Eschscholtzia californica stigmas with germinating pollen at different stages of development were the subject of histochemical studies which aimed the localization of several enzymes like phosphorylase, leucine amino peptidase, nonspecific esterase, cytochrome oxidase, aldolase, alpha-glycerophosphate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, monoamine oxidase, alpha-galactosidase, beta-glucosidase and beta-galactosidase. Pollen and pollen tubes were shown to contain starch, lipid, proteins and soluble sugars as the storage products. These storage products were utilized during germination and tube growth. The role of different enzymes in the process of germination and tube growth is discussed. From the distribution of oxidoreductases it is inferred that respiration plays an essential role in the tube growth. During pollen germination probably the reserve proteins were transported to pollen tube tip. The increase of activity of alpha-and beta-galactosidase in pollen tubes indicates on their involvement in carbohydrate metabolism. The role of alpha-galactosidase in the metabolism of galactolipids is also inferred. Similarly, the reaction catalysed by beta-glucosidase resulted in the production of aglycon and glucose; of these the former possibly act as a substrate of peroxidase. Some of the glycosidases diffused out of pollen wall on the stigma and participated in the release of free sugars of the female tissue.
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PMID:Studies on the physiology of pollen and pollen tube growth. IV Eschscholtzia californica Cham. 22 Jan 58

The glpE gene of E. coli was found to be transcribed divergently with respect to glpD, which is adjacent to glpE head-to-head on the E. coli chromosome. We constructed glpD- and/or glpE-lacZ fusion plasmids, which provided glpD and lacZ as reporter genes. The expression of glpD and glpE, under the control of the cAMP-CRP complex, was examined by measuring the activities in E. coli cells of beta-galactosidase encoded by lacZ and glycerol-3-phosphate dehydrogenase encoded by glpD. In the double-reporter-gene system, the expression of glpD and glpE was found to be positively regulated by cAMP-CRP. We also confirmed that intracellular levels of the translation products and the transcripts from glpD and glpE were positively regulated by cAMP-CRP. The cAMP-mediated induction of gene expression of glpD and glpE was significantly affected by structural alterations of the single CRP-binding site between glpD and glpE. These results indicate that the single CRP-binding site is a cis-acting element involved in the positive regulation of the expression of both glpD and glpE at the transcriptional level.
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PMID:Regulation of glpD and glpE gene expression by a cyclic AMP-cAMP receptor protein (cAMP-CRP) complex in Escherichia coli. 184 66

Region 26A of the second chromosome of Drosophila melanogaster has been extensively characterized at the genetic level. We report here the cloning of virtually the entire 26A region via a bidirectional chromosome walk. Deletion and translocation breakpoints in the 26A interval have been localized at the molecular level by both chromosomal in situ hybridization and Southern analysis. The locations of the genetically defined loci in this chromosomal region have also been correlated with transcriptional units mapped onto the DNA of the proximal region of the chromosomal walk. The position of the alpha-glycerophosphate dehydrogenase (alpha-Gpdh) gene in 26A5-7 has been confirmed and a putative transcriptional unit for the beta-galactosidase-1 (beta-Gal-1) gene has been identified in the 26A7-9 interval.
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PMID:Molecular cloning and analysis of the chromosomal region 26A of Drosophila melanogaster. 190 3

The glpD gene encoding aerobic sn-glycerol-3-phosphate dehydrogenase of Escherichia coli K-12 was cloned into pACYC177 from a lambda glpD transducing phage. The recombinant plasmid, designated pSH55, carried a 7.4-kilobase-pair HindIII fragment containing the glpD and glpR genes. The glpD gene was subcloned into pACYC177 on a 4.4-kilobase-pair BamHI-HindIII fragment. Expression of the cloned glpD gene was regulated in the manner previously described for the chromosomal glpD gene. The position of glpD on this plasmid was determined by Tn1000 insertional inactivation experiments. The glpD gene product, a polypeptide of Mr 55,000, was detected in a maxicell system. Truncated polypeptides replaced the 55,000-molecular-weight polypeptide when plasmid derivatives harboring Tn1000 insertions that inactivate glpD were used as templates. The sizes of these polypeptides confirmed the previously determined direction of transcription and allowed estimation of the translation start site. Determination of the apparent Mr of a hybrid protein encoded by a glpD'-'lacZ fusion provided additional evidence for the position of the glpD control region. The amino-terminal 30 to 60 amino acids of this hybrid protein (provided by glpD) were sufficient for efficient membrane localization of glpD'-'lacZ-encoded beta-galactosidase activity. The glpD3 mutation was mapped within the glpD gene, providing additional evidence that glpD is the structural gene for aerobic sn-glycerol-3-phosphate dehydrogenase.
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PMID:Cloning and characterization of the aerobic sn-glycerol-3-phosphate dehydrogenase structural gene glpD of Escherichia coli K-12. 302 31

A procedure has been devised that allows selection of mutants defective in the beta-methylgalactoside transport system (mgl) of Escherichia coli. This procedure utilizes the compound 2R-glyceryl-beta-d-galactopyranoside (glycerylgalactoside), which is known to be transported by only two transport system in E. coli, namely, the lactose and the beta-methylgalactoside transport systems. Mutants lacking glycerol-3-phosphate dehydrogenase (glpD) are sensitive to glycerol. Similarly, mutants lacking uridine diphosphate-galactose-4-epimerase (galE) are sensitive to galactose. Glycerylgalactoside is an inducer of the lactose operon and also a substrate for beta-galactosidase. Thus, a mgl(+)glpD galE lacY strain will not grow in the presence of glycerylgalactoside owing to accumulated glycerol-3-phosphate, galactose-1-phosphate, and uridine diphosphate-galactose. We have constructed such a strain and shown that mgl mutants can be obtained by selecting for those that grow in the presence of glycerylgalactoside.
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PMID:Selection procedure for mutants defective in the beta-methylgalactoside transport system of Escherichia coli utilizing the compound 2R-glyceryl-beta-D-galactopyranoside. 460 64

In order to relate the biogenesis of the lactose transport system to lipid synthesis, a glycerol-requiring mutant of Escherichia coli K-12 with a specific defect in l-glycerol-3-phosphate synthesis was isolated and characterized. The defective enzyme is the biosynthetic l-glycerol-3-phosphate dehydrogenase [l-glycerol-3-phosphate: NAD (P) oxidoreductase, EC 1.1.1.8] which functions as a dihydroxyacetone phosphate reductase to provide l-glycerol-3-phosphate for lipid synthesis. In this mutant, removal of glycerol from the growth medium results in inhibition of the synthesis of protein, deoxyribonucleic acid, and phospholipid. Inhibition of phospholipid synthesis immediately follows glycerol removal, whereas the inhibition of deoxyribonucleic acid and protein synthesis is preceded by a short lag period. Glycerol starvation does not change the turnover pattern of previously synthesized phospholipids. The blocking of lipid synthesis by glycerol starvation causes a drastic decrease in inducibility of beta-galactoside transport activity relative to beta-galactosidase, indicating that induction of lactose transport requires de novo lipid synthesis.
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PMID:Induction of the lactose transport system in a lipid-synthesis-defective mutant of Escherichia coli. 491 67

P element-mediated transformation has been used to investigate the regulation of expression of the sn-glycerol-3-phosphate dehydrogenase gene of Drosophila melanogaster. A 13-kb construct containing the eight exons and associated introns, 5 kb of the 5' region, and 3 kb downstream from the structural gene produced normal levels of enzyme activity and rescued the poor viability of flies lacking the enzyme. All the regulatory elements essential for normal enzyme expression were located in a fragment that included the exons and introns and 1-kb upstream noncoding sequence. Deletions of the 1.6-kb second intron reduced activity to 25%. Transformants with fusion constructs between the sn-glycerol-3-phosphate dehydrogenase gene and the beta-galactosidase gene from E. coli revealed three elements that affected expression. A (CT)9 repeat element at the 5' end of the second intron increased expression in both larvae and adults, particularly at emergence. A second regulatory element, which includes a (CT)7 repeat, was located 5' to the TATA box and had similar effects on the gene's expression. A third, undefined, enhancer was located in the second intron, between 0.5 and 1.8 kb downstream of the translation initiation codon. This element increases enzyme activity to a similar extent in larvae and adults but has little effect when the enhancer at the 5' end of the intron is present.
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PMID:Regulation of the expression of the sn-glycerol-3-phosphate dehydrogenase gene in Drosophila melanogaster. 991 59