Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.1.18 (branching enzyme)
 628 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using the glgB gene from Escherichia coli as a hybridization probe, the gene encoding the branching enzyme of the cyanobacterium Synechococcus sp. PCC7942 has been identified on a 3.9-kb PstI fragment which was cloned into plasmid pUC9. Two types of plasmids have been isolated. Plasmid pKVN1 was expressing the Synechococcus sp. gene as was shown by complementation of the glgB mutation of E. coli KV832. Plasmid pKVN2, which carried the same insert in the opposite orientation was unable to complement E. coli KV832, indicating that the promoter of the cloned gene was either absent or was not recognized in E. coli. Determination of branching activity in extracts of Synechococcus sp. and E. coli KV832[pKVN1] showed that the enzyme was optimally active at approximately 35 degrees C. No significant activity was present at temperatures higher than 55 degrees C, reflecting the mesophilic nature of the cloned enzyme. In a cell-free coupled transcription-translation system the cloned gene specified two proteins of 84 kDa and 72 kDa, respectively, which are probably translated independently from the same gene by initiation at two different start codons.
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PMID:Cloning and expression of the branching enzyme gene (glgB) from the cyanobacterium Synechococcus sp. PCC7942 in Escherichia coli. 252 79

Inclusion bodies containing glycogen-enzymes were found in 30 to 60% of type 2 fibres of tenotomized calf muscles (m. gastrocnemius, m. soleus, m. plantaris) in rats, using histochemical reactions. The bodies appeared within 1 week after the tenotomy and were localized both in the central and the subsarcolemmal regions and rarely extruded into the extracellular space. These aggregates are 3 to 15 microns in length and 2 to 11 microns in diameter. In addition to glycogen, these bodies also contained various enzymes of the glycogen metabolism such as phosphorylase, a branching enzyme, and glucose-6-phosphatase, but showed no NADH-reductase, lactate dehydrogenase, or myofibrillar ATP-ase activity. The results indicate that glycogen-enzymes containing bodies are a degenerative phenomenon, which occurs only in type 2 fibres of the tenotomized muscles.
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PMID:Glycogen-enzymes containing bodies in type 2 fibres of tenotomized muscles in the rat. 255 27

A first Japanese case of an adult polysaccharide storage myopathy (APSM) was reported. A 30-year-old Japanese male was admitted because of weakness of the lower limbs. The onset of the symptoms was at the age of 23. Neurologically he had moderate weakness of proximal limb muscles involving the lower limbs more than the upper and slightly decreased vibratory sense in the feet. His gait was waddling. The following laboratory values were obtained; SGOT 45 I.U., SGPT 83 I.U., CPK 218 I.U., UA 8.3 mg/dl. Ischemic exercise test of the forearm showed a normal rise of venous lactate. EMG revealed a mixture of myopathic and mild neurogenic patterns characterized by motor units of short duration and low amplitude with intermittent high amplitude potentials, fibrillation and fasciculation. There were also prominent myotonic discharges without clinical myotonia. MCV was normal, however sural nerve SCV was slightly slow (lt. 36/m, rt. 38 m/s). Muscle biopsy revealed vacuolar myopathy. Most vacuoles contained basophilic, PAS-positive, diastase-resistant and Lugol's iodine-negative material. With ATPase staining there was type 1 fiber predominance (84%), but the vacuoles were predominantly seen in type 2A fiber. In ultrastructural study, the storage material was located under the sarcolemma and in the areas of the intermyofibrillar network. No delimiting membranes were seen. At higher magnification, these masses were consisted of filaments. Therefore the storage material was considered to be unusual polysaccharide. Glycogen storage disease was suspected, however, biochemical study of the muscle specimen disclosed no enzymatic defect including branching enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Adult polysaccharide storage myopathy]. 269 Nov 65

A correlation between increased beta-1,6 branching of N-linked carbohydrates and the ability of a cell to metastasize or to form a tumor has been observed in several experimental models. Lec9 Chinese hamster ovary (CHO) mutants exhibit a drastic reduction in tumorigenicity in nude mice, and this phenotype directly correlates with their ability to attach an increased proportion of beta-1,6-branched carbohydrates to the G glycoprotein of vesicular stomatitis virus (J. Ripka, S. Shin, and P. Stanley, Mol. Cell. Biol. 6:1268-1275, 1986). In this paper we provide evidence that cellular carbohydrates from Lec9 cells also contain an increased proportion of beta-1,6-branched carbohydrates, although they do not possess significantly increased activity of the beta-1,6 branching enzyme (GlcNAc-transferase V). Biosynthetic labeling experiments show that a substantial degree of underglycosylation occurs in Lec9 cells and that this affects several classes of glycoproteins. Lec9 cells synthesize ca. 40-fold less Glc3Man9GlcNAc2-P-P-lipid and ca. 2-fold less Man5GlcNAc2-P-P-lipid than parental cells do. In addition, Lec9 cells possess ca. fivefold less protein-bound oligosaccharide intermediates, and one major species is resistant to release by endo-beta-N-acetylglucosaminidase H (endo H). Membranes of Lec9 cells exhibit normal mannosylphosphoryldolichol synthase, glucosylphosphoryldolichol synthase, and N-acetylglucosaminylphosphate transferase activities in the presence of exogenous dolichyl phosphate. However, in the absence of exogenous dolichyl phosphate, mannosylphosphoryldolichol synthase and glucosylphosphoryldolichol synthase activities are reduced in membranes of Lec9 cells, indicating that membranes of Lec9 cells are deficient in lipid phosphate. This was confirmed by analysis of lipids labeled by [3H]mevalonate, which showed that Lec9 cells have less lipid phosphate than parental CHO cells. Mechanisms by which a defect in the synthesis of dolichol-oligosaccharides might alter the degree of beta-1,6 branching in N-linked carbohydrates are discussed.
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PMID:Control of carbohydrate processing: increased beta-1,6 branching in N-linked carbohydrates of Lec9 CHO mutants appears to arise from a defect in oligosaccharide-dolichol biosynthesis. 272 6

1. Branching enzymes from rat and rabbit liver, as well as from potato and maize were prepared. They were almost free from contaminating glucan-degrading enzymes. 2. In 'sweet corn' maize, two separate fractions with (alpha 1,4)glucan: (alpha 1,4)glucan alpha 6-glycosyltransferase activities were obtained. One of them synthesized amylopectin, the branched component of starch, in the presence of phosphorylase and Glc1P, while the other fraction synthesized phytoglycogen. Furthermore, in a maize variety which does not accumulate phytoglycogen, only one fraction of branching activity was found, that formed amylopectin under the above-mentioned conditions. 3. Comparative analyses performed with native (alpha 1,4)-(alpha 1,6)glucopolysaccharides, and those synthesized in vitro with the branching enzyme from the same tissue, demonstrated a close similarity between both glucans. 4. It may be concluded that the branching enzyme is responsible for the specific degree of (alpha 1,6) branch linkages found in the native polysaccharide.
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PMID:The degree of branching in (alpha 1,4)-(alpha 1,6)-linked glucopolysaccharides is dependent on intrinsic properties of the branching enzymes. 295 76

Streptococcus mutans secretes a sucrose-independent branalphang enzyme that utilizes isomaltosaccharides as donors for branalphang formation on dextran. Although the branching enzyme is necessary for the formation of extracellular polysaccharide complexes, the source of the donor for the enzyme is unknown. In this study, we purified a novel glucosyltransferase from S. mutans and characterized its properties. The glucosyltransferase was primer independent 1,6-alpha-D-glucan synthase, which produced oligo-isomaltosaccharides. The enzyme was thought to be a source of donor for the branching enzyme in S. mutans.
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PMID:A novel glucosyltransferase from Streptococcus mutans produces oligo-isomaltosaccharides. 296 30

In this paper we elucidate part of the mechanism of the early stages of the biosynthesis of glycogen. This macromolecule is constructed by covalent apposition of glucose units to a protein, glycogenin, which remains covalently attached to the mature glycogen molecule. We have now isolated, in a 3500-fold purification, a protein from rabbit muscle that has the same Mr as glycogenin, is immunologically similar, and proves to be a self-glucosylating protein (SGP). When incubated with UDP-[14C]glucose, an average of one molecular proportion of glucose is incorporated into the protein, which we conclude is the same as glycogenin isolated from native glycogen. The native SGP appears to exist as a high-molecular-weight species that contains many identical subunits. Because the glucose that is self-incorporated can be released almost completely from the acceptor by glycogenolytic enzymes, the indication is that it was added to a preformed chain or chains of 1,4-linked alpha-glucose residues. This implies that SGP already carries an existing maltosaccharide chain or chains to which the glucose is added, rather than glucose being added directly to protein. The putative role of SGP in glycogen synthesis is confirmed by the fact that glucosylated SGP acts as a primer for glycogen synthase and branching enzyme to form high-molecular-weight material. SGP itself is completely free from glycogen synthase. The quantity of SGP in muscle is calculated to be about one-half the amount of glycogenin bound in glycogen.
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PMID:A self-glucosylating protein is the primer for rabbit muscle glycogen biosynthesis. 297 23

The nucleotide sequences of the Escherichia coli genome between the glycogen biosynthetic genes glgB and glgC, and 1170 bp of DNA which follows glgA have been determined. The region between glgB and glgC contains an open reading frame (ORF) of 1521 bp which we call glgX. This ORF is capable of coding for an Mr 56,684 protein. The deduced amino acid (aa) sequence for the putative product shows significant similarity to the E. coli glycogen branching enzyme, and to several different glucan hydrolases and transferases. The regions of sequence similarity include residues which have been reported to be involved in substrate binding and catalysis by taka-amylase. This suggests that the proposed product may catalyze hydrolysis or glycosyl-transferase reactions. The cloned region which follows glgA contains an incomplete ORF (1149 bp), glgY, which appears to encode 383 aa of the N terminus of glycogen phosphorylase, based upon sequence similarity with the enzyme from rabbit muscle (47% identical aa residues) and with maltodextrin phosphorylase from E. coli (37% identical aa residues). Results suggest that neither ORF is required for glycogen biosynthesis. The localization of glycogen biosynthetic and degradative genes together in a cluster may facilitate the regulation of these systems in vivo.
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PMID:Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes. 297 49

Activities of glycogen synthase (total) and branching enzyme in slow (soleus) muscle are higher than those in fast (vastus lateralis) muscle, while those of phosphorylase kinase (total), phosphorylase (total) and debranching enzyme are reversed. The active form ratio of glycogen synthase is higher in fast muscle, while those of phosphorylase kinase and phosphorylase are higher in slow muscle. Activities of cAMP-dependent protein kinase and protein phosphatase in slow muscle are higher than those in fast muscle. These results suggest that glycogen metabolizing enzymes in slow muscle, distinct from those in fast muscle, are regulated more strongly by cAMP-dependent protein kinase rather than by protein phosphatase.
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PMID:Comparison of enzyme activities on glycogen metabolism in rabbit slow and fast muscles. 299 76

A mutant strain of Escherichia coli K-12, designated 618, accumulates glycogen at a faster rate than wild-type strain 356. The mutation affects the ADPglucose pyrophosphorylase regulatory properties (N. Creuzat-Sigal, M. Latil-Damotte, J. Cattaneo, and J. Puig, p. 647-680, in R. Piras and H. G. Pontis, ed., Biochemistry of the Glycocide Linkage, 1972). The enzyme is less dependent on the activator, fructose 1,6 bis-phosphate for activity and is less sensitive to inhibition by the inhibitor, 5'-AMP. The structural gene, glgC, for this allosteric mutant enzyme was cloned into the bacterial plasmid pBR322 by inserting the chromosomal DNA at the PstI site. The glycogen biosynthetic genes were selected by cotransformation of the neighboring asd gene into an E. coli mutant also defective in branching enzyme (glgB) activity. Two recombinant plasmids, pEBL1 and pEBL3, that had PstI chromosomal DNA inserts containing glgC and glgB were isolated. Branching enzyme and ADPglucose pyrophosphorylase activities were increased 240- and 40-fold, respectively, in the asd glgB mutant, E. coli K-12 6281. The E. coli K-12 618 mutant glgC gene product was characterized after transformation of an E. coli B ADPglucose pyrophosphorylase mutant with the recombinant plasmid pEBL3. The kinetic properties of the cloned ADPglucose pyrophosphorylase were similar to those of the E. coli K-12 618 enzyme. The inserted DNA in pEBL1 was arranged in opposite orientation to that in pEBL3.
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PMID:Cloning and expression of the Escherichia coli glgC gene from a mutant containing an ADPglucose pyrophosphorylase with altered allosteric properties. 301 41


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