Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

In lysosomes beta-galactosidase and neuraminidase acquire a stable and active conformation through their association with the protective protein. The latter is homologous to serine carboxypeptidases and has cathepsin A-like activity which is distinct from its protective function towards the two glycosidases. To define signals in the human protective protein important for its intracellular transport, and to determine the site of its association with beta-galactosidase, we have generated a set of mutated protective protein cDNAs carrying targeted base substitutions. These mutants were either singly transfected into COS-1 cells or cotransfected together with wild type human beta-galactosidase. We show that all point mutations cause either a complete or partial retention of the protective protein precursor in the endoplasmic reticulum. This abnormal accumulation leads to degradation of the mutant proteins probably in this compartment. Only the oligosaccharide chain on the 32-kDa subunit acquires the mannose 6-phosphate recognition marker, the one on the 20-kDa subunit seems to be merely essential for the stability of the mature protein. In cotransfection experiments, wild type beta-galactosidase and protective protein appear to assemble already as precursors, soon after synthesis, in the endoplasmic reticulum. Mutated protective protein precursors that are retained in the endoplasmic reticulum or pre-Golgi complex interact with and withhold normal beta-galactosidase molecules in the same compartments, thereby preventing their normal routing.
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PMID:Human lysosomal protective protein. Glycosylation, intracellular transport, and association with beta-galactosidase in the endoplasmic reticulum. 138 45

The beta-galactosidase activities arising from Tn5lac insertions in several genes required for antibiotic TA production were measured under different growth conditions. In all of the non-TA-producing mutants, the beta-galactosidase specific activity was higher when the cells were grown in nutrient-limited 0.5CTS medium (0.5% Casitone plus alanine, serine, and glucose) than in rich 2CT medium (2% Casitone). One of the mutants, 420, had low beta-galactosidase specific activity in both media. The other seven mutants containing inserts in genes essential for TA production had specific activities of 139 to 367 U/mg of protein in 0.5CTS medium and 11 to 48 U/mg of protein in 2CT medium. The beta-galactosidase specific activities of two strains, 1030 and 420, increased during exponential growth in 0.5CTS medium. The beta-galactosidase specific activities of both strains increased greatly when the cells were grown in the presence of magnesium phosphate, which traps ammonium ions. The Tn5lac insertions in 1030 and 420 were used to screen for mutants with increased levels of transcription. An N-methyl-N'-nitro-N-nitrosoguanidine-induced mutation in 1030 that mapped 17 kb from the omega 1010 insert increased the specific activity of beta-galactosidase 21 times in 2CT medium. The regulatory mutation appears to release the repression caused by 2CT medium. A UV-induced mutation in 420 increased the beta-galactosidase specific activity 1.4 to 2.4 times. Medium conditions that affect the transcription of TA genes are discussed in terms of enhanced antibiotic TA production.
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PMID:Use of Tn5lac to study expression of genes required for production of the antibiotic TA. 144 12

Transfection of the beta-galactosidase gene in quiescent cultures of adult rat hepatocytes with the calcium phosphate precipitate or the lipofection methods gave a higher level of beta-galactosidase gene expression with the lipofection than with the calcium phosphate precipitate method, but the transfection efficiency was weak in both cases. Transfection of hepatocytes stimulated to proliferate before transfection either in vivo by partial hepatectomy or in vitro by epidermal growth factor was more efficient than transfection of quiescent hepatocytes, and the lipofection method gave better results than the calcium phosphate precipitate method.
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PMID:Increased efficiency of gene transfection in primary cultures of adult rat hepatocytes stimulated to proliferate: a comparative study using the lipofection and the calcium phosphate precipitate methods. 151 43

Swarm rat chondrosarcoma cell cultures were metabolically labeled with [35S]sulfate, [3H]glucose, or [3H]glucosamine. Chondroitin sulfate chains were isolated from purified aggrecan using alkaline borohydride treatment and Superose 6 chromatography. Various linkage region oligosaccharide alditols were derived from these chains using sequential chondroitinase digestions (ABC lyase followed by ACII lyase). They were then further processed by mercuric acetate treatment, which removed the 4,5-unsaturated uronosyl residue from the nonreducing end of the linkage, and then beta-galactosidase digestion which liberated the 2 galactose residues from the xylitol reducing terminus. Alkaline phosphatase digestions were performed to verify the presence of phosphate esters. All linkage region structures were isolated and identified using a combination of Progel-TSK G2500 and CarboPac PA1 chromatography steps in conjunction with monosaccharide analyses. This study revealed that chondroitin sulfate chains from aggrecan synthesized by rat chondrosarcoma cells in vitro have the following properties: 1) three out of every four of their linkage regions carry a phosphate ester on xylose, 2) nearly three out of every five chains begin the repeating disaccharide region with an unsulfated first disaccharide unit, 3) nearly twice as many nonphosphorylated chains have a sulfated first disaccharide than their phosphorylated counterparts, and 4) the vast majority of these chains do not contain sulfated galactose in their linkage regions. This report also describes a borohydride reduction procedure to confer alkali stability to the 3-substituted, unsaturated disaccharides derived from chondroitinase digests of chondroitin sulfate. Furthermore, a CarboPac PA1 method is demonstrated that separates these reduced disaccharides with exceptional resolution.
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PMID:Structural analysis of the linkage region oligosaccharides and unsaturated disaccharides from chondroitin sulfate using CarboPac PA1. 155 66

A series of chemically synthesized oligomannosides that contain mannose 6-phosphate residues were utilized as inhibitors of the binding of beta-galactosidase to high (CI-MPR, 215 kDa) and low (CD-MPR, 41-46 kDa) molecular mass mannose 6-phosphate receptor from bovine testes in order to probe the specificity of each receptor. Mannobioside phosphorylated in the terminal position and linked alpha(1,2) was a 6-fold better inhibitor than the corresponding alpha(1,3)- and alpha (1,6)-linked isomers. Inhibition observed with a monophosphorylated alpha(1,2)-linked mannotrioside was approximately 6-fold greater than that with the corresponding mannobioside. Penultimate glycosidic linkages of the oligomannosides played little or no role in the inhibition of binding of ligand to the receptors. Monophosphorylated oligomannosides containing phosphomonoester groups on penultimate mannose residues were not inhibitors. Binding inhibition observed for biantennary oligomannosides with phosphate on terminal mannose residues of either alpha(1,3) or alpha(1,6) chains closely approximated the values obtained with analogous trimannosides. A biantennary oligomannoside on which each antennary chain contained a terminal phosphate exhibited approximately an 8-fold greater inhibition than monophosphorylated compounds. Although the receptors exhibited similar relative specificities for phosphomonoesters, phosphodiesters did not inhibit binding of ligand to CD-MPR and only weakly inhibited binding to CI-MPR.
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PMID:The binding specificity of high and low molecular weight phosphomannosyl receptors from bovine testes. Inhibition studies with chemically synthesized 6-O-phosphorylated oligomannosides. 165 78

After NIH3T3 cells constitutively expressing T7 RNA polymerase were transfected (+ Ca.phosphate) with a circular DNA containing the firefly luciferase(Luc)-encoding gene (luc) 3' to the encephalomyocarditis (EMC) virus 5'-untranslated sequence and T7 promoter, Luc protein comprising approx. 20% of total cellular protein was obtained. After similar transfection of an analogous construct containing the lacZ gene into the same cell line, at least 50% of the cells produced beta-galactosidase. Fibroblasts lipofected with uncapped RNA transcripts containing EMC sequence expressed the reporter genes as efficiently as capped transcripts. A novel approach was used to generate RNA transcripts containing poly(A) at its very 3' end. RNA from a luc vector with a poly(A) sequence at the very 3' end produced 20-fold more Luc than the RNA from the same vector with an additional 3' nonpoly(A) sequence. These results suggest that this T7 RNA polymerase expression system will be useful for the efficient production of proteins in mammalian cells.
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PMID:High-efficiency protein synthesis from T7 RNA polymerase transcripts in 3T3 fibroblasts. 166 54

In the small intestine lactose is subjected to the hydrolytic impact of beta-galactosidase originating mainly from the mucosa. In rats about two thirds of the enzyme activity are located in the first part of the small intestine, and one third in the second one. A part of the mucosal enzyme does not remain in the mucosa. It becomes detached and can be determined in the chymus. The ratio of the transient to the resident proportion amounts to 1.8: 1 in germfree and 0.23: 1 in conventional rats. Bacterial settlement causes an increase in the mucosal mass resulting in higher total activity whereas the specific activity of the mucosal enzyme remains unchanged. Microorganisms occurring close to the small intestine mucosa take part in lactose degradation. Lactose-containing diet leads to an increase in both the bacterial and the mucosal activity, the latter one to varying degrees. Lactose concentration in the ileal chymus rises with increasing intake of lactose and decreasing protein and phosphate intake. Following a saturation kinetics the velocity of lactose hydrolysis is correlated with the lactose concentration of the diet. alpha-lactose is hydrolysed more rapidly in the small intestine of both human sucklings and rats than beta-lactose. As the results of a mathematical model show lactose mutarotation does not effect on the degree of lactose degradation in the small intestine. Depending on the intake of lactose and the food composition the rate of lactose hydrolysis amounts to: --max. 50% after small intestine perfusion in human sucklings, --max. 80% after small intestine perfusion in rats, --max. 60% in rats with ileostomata.
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PMID:[Lactose--a potential dietary fiber. The regulation of its microecological effect in the intestinal tract. 2. The nutrient effect of lactose]. 166 54

The activity of the mucosal beta-galactosidase of caecum and colon is low in both germfree and conventional rats. beta-Galactosidase activity occurs also in the chymus of germfree rats. It increases after monoassociation and is higher in conventional than in germfree animals. Lactose entering caecum and colon acts like dietary fibre and is hydrolysed mainly by the intestinal flora. Aerobe lactobacilli and bacteroides predominate in the microflora of rat caecum and colon. A lactose-containing diet increases the total number of germs and stimulates the growth of bifidobacteria. After special diets, rich in lactose and low in protein and phosphate (e.g. human milk and similar formulae), the number of bacteroides and other putrefactive germs decreases. Moreover, a lactose-containing diet alters the metabolic activity of intestinal microorganisms (activity of microbial beta-galactosidase, acidification and lowering of ph in the chymus, production of hydrogen, proteolytic activity.) Lactose as dietary fibre decreases the nitrogen excretion in the urine and increases the N-excretion in the faeces of conventional rats.
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PMID:[Lactose--a potential dietary fiber. The regulation of its microecologic effect in the intestinal tract. 3. Dietary fiber actions of lactose due to microbial activity]. 166 42

The conditions and the intestinal processes responsible for the action of lactose as a potential dietary fibre are described. The beta-galactosidase activity in the rat caecum and colon is influenced by dietary factors: It declines with increasing lactose concentration and it rises with increasing protein and phosphate concentration in the diet. The enzyme activity correlates negatively with the content of lactose, and positively with the content of protein and phosphate in the chymus. The products of lactose hydrolysis are degraded by microbial glycolysis in caecum and colon. The glycolytic products are mainly absorbed and energetically utilized by the macroorganism. Phosphate stimulates the microbial metabolism and, therefore, accelerates the consumption of the energy substrate lactose. Mathematical optimization gives the necessary composition of the diet which causes an intended microecological effect. To minimize the chymus pH (5.1 in the colon ascendens; 4.6 in the colon descendens; 4.3 in the faeces) the lactose content of the diet has to be greater than or equal to 160 mumol/g, the protein content less than or equal to 10 mg/g, and the phosphate content less than or equal to 5.5 mumol/g. The minimal pH value depends to a greater extent on variations in the supply of protein and phosphorus with the diet whereas the response to changes in lactose concentration is less noticeable.
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PMID:[Lactose--a potential dietary fiber. The regulation of its microecologic effect in the intestinal tract. 4. Dietary fiber action of lactose: evaluation with multivariate statistical analysis]. 166 43

A convenient means was devised for the purification of milligram quantities of a soluble form of the mannose 6-phosphate/insulin-like growth factor II receptor (Man-6-P/IGF II receptor). The receptor was purified to near homogeneity from bovine serum by affinity chromatography on agarose-pentamannosephosphate in the absence of detergent. Approximately 2.5 mg of receptor were obtained from 500 ml of fetal calf serum. The concentration of receptor in serum decreased sharply with development. Fetal calf serum Man-6-P/IGF II receptor was immunologically similar to detergent-solubilized, membrane-bound Man-6-P/IGF II receptor from bovine liver. N-Terminal sequence analysis revealed that the purified serum receptor, but not the solubilized, membrane-associated receptor, contains stoichiometric amounts of bound IGF II. The results of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel chromatography studies suggest that the fetal calf serum receptor (in contrast to the solubilized, membrane-bound bovine testis receptor) does not aggregate. The affinity of the fetal calf serum receptor for bovine testis beta-galactosidase approximated one-half that observed for solubilized, membrane-bound bovine testis receptor.
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PMID:Isolation and characterization of mannose 6-phosphate/insulin-like growth factor II receptor from bovine serum. 166 5


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