Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Saccharomyces strains capable of fermenting maltose contain any one of five telomere-associated MAL loci. Each MAL locus is a complex of three genes encoding the three functions required to ferment maltose: maltose permease (GENE 1), maltase (GENE 2) and the MAL trans-activator (GENE 3). All five loci have been cloned and all are highly sequence homologous over at least a 9.0 kbp region containing these GENEs (Charron et al., Genetics 122, 307-331, 1989). Our initial studies of strains carrying the MAL3 locus indicated the presence of linked, repeated MAL-homologous sequences (Michels and Needleman, Mol. Gen. Genet. 191, 225-230, 1983). Here we report our analysis of the centromere-proximal MAL3-linked sequences and show that the complete MAL3 locus spans approximately 40 kbp and consists of tandemly arrayed, partial repeats of the three GENE sequences described above. In addition, the structure of the MAL3 locus is compared to that of three partially functional alleles of MAL3. These alleles were shown to contain only MAL31 and MAL32 and their structure suggests that they resulted from MAL3 deletions removing the sequences centromere-proximal to MAL31. The amplification and rearrangement of the telomere-linked MAL3 sequences are discussed in the context of studies on other telemere-associated sequences from yeast and other species.
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PMID:The telomere-associated MAL3 locus of Saccharomyces is a tandem array of repeated genes. 144 45

The aga gene coding for alpha-galactosidase in Streptococcus mutans was detected in a recombinant gene library constructed in phage lambda. The gene was subcloned into plasmid vectors and shown to specify a novel protein of Mr 80,000. Characterization of alpha-galactosidase from S. mutans and from recombinant Escherichia coli expressing aga indicated that the enzyme functions as a tetramer. The amino acid composition of the alpha-galactosidase, deduced from nucleotide sequencing of aga, gave a predicted Mr of 82,022 and revealed regions of homology to alpha-galactosidases encoded by the E. coli Raf plasmids and by Bacillus stearothermophilus. Inactivation of the aga gene in S. mutans resulted in loss of all alpha-galactosidase activity and abolished the ability to ferment melibiose; alpha-glucosidase activity was also lost, due to an indirect effect on the dexB gene.
J Gen Microbiol 1991 Apr
PMID:Biochemical and genetic analysis of Streptococcus mutans alpha-galactosidase. 166 Sep 18

1. The effect of the alpha-glucosidase inhibitor Acarbose on integrated glycemic control and on nonenzymatic glycation of glomerular basement membrane was examined in streptozotocin diabetic rats. 2. Treatment with Acarbose for 8 weeks after induction of diabetes significantly reduced the level of HbA1c and of glomerular basement membrane glycation. 3. Acarbose exerts a significant antihyperglycemic effect and has a salutary influence on the nephropathic process in experimental diabetes.
Gen Pharmacol 1991
PMID:Effect of alpha-glucosidase inhibition on the nonenzymatic glycation of glomerular basement membrane. 186 25

1. The effect of the alpha-glucosidase inhibitor Acarbose on collagen fluorescence reflecting formation of advanced glycation end products was examined in streptozotocin-diabetic rats. 2. Treatment with Acarbose for eight weeks after induction of diabetes prevented the increased fluorescence in skin and tail tendon collagen associated with untreated diabetes. 3. Acarbose improves integrated glycemic control and beneficially influences the consequences of excess glycation in long-lived connective tissue proteins.
Gen Pharmacol 1991
PMID:Alpha-glucosidase inhibition prevents increased collagen fluorescence in experimental diabetes. 193 95

In hex2 mutants of Saccharomyces cerevisiae, which are defective in glucose repression of several enzymes, growth is inhibited if maltose is present in the medium. After adding [14C]maltose to cultures growing with ethanol, maltose metabolism was followed in both hex2 mutant and wild-type cells. The amount of radioactivity incorporated was much higher in hex2 than in wild-type cells. Most of the radioactivity in hex2 cells was located in the low molecular mass fraction. Pulse-chase experiments showed that 2 h after addition of maltose, hex2 cells hydrolysed maltose to glucose, which was partially excreted into the medium. 31P-NMR studies gave evidence that turnover of sugar phosphates was completely abolished in hex2 cells after 2 h incubation with maltose. 13C-NMR spectra confirmed these results: unlike those for the wild-type, no resonances corresponding to fermentation products (ethanol, glycerol) were found for hex2 cells, whereas there were resonances corresponding to glucose. Although maltose is taken up by proton symport, the internal pH in the hex2 mutant did not change markedly during the 5 h after adding maltose. The intracellular accumulation of glucose seems to explain the inhibition of growth by maltose, probably by means of osmotic damage and/or unspecific O-glycosylation of proteins. Neither maltose permease nor maltase was over-expressed, and so these enzymes were not the cause of glucose accumulation. Hence, the coordination of maltose uptake, hydrolysis to glucose and glycolysis of glucose is not regulated simply by the specific activity of the catabolic enzymes involved.(ABSTRACT TRUNCATED AT 250 WORDS)
J Gen Microbiol 1990 May
PMID:Misregulation of maltose uptake in a glucose repression defective mutant of Saccharomyces cerevisiae leads to glucose poisoning. 219 4

Multigene families are a ubiquitous feature of eukaryotes; however, their presence in Saccharomyces is more limited. The MAL multigene family is comprised of five unlinked loci, MAL1, MAL2, MAL3, MAL4 and MAL6, any one of which is sufficient for yeast to metabolize maltose. A cloned MAL6 locus was used as a probe to facilitate the cloning of the other four functional loci as well as two partially active alleles of MAL1. Each locus could be characterized as a cluster of three genes, MALR (regulatory), MALT (maltose transport or permease) and MALS (structural or maltase), encoded by a total of about 7 kb of DNA; however, homologous sequences at each locus extend beyond the coding regions. Our results indicate that there is extensive homology among the MAL loci, especially within their maltase genes. The greatest sequence diversity occurs in their regulatory gene regions. Southern cross analyses of the cloned MAL loci indicate a single duplication of the MAL6R-homologous sequences upstream of the MAL6R gene as well as an extensive duplication of more than 10 kb at the MAL3 locus. The large repeat at the MAL3 locus results in the presence of four copies of MAL3R-homologous sequences and two copies of MAL3T-homologous sequences at that locus. Two naturally occurring inactive alleles of MAL1 show a deletion or divergence of their MALR sequences. The significance of these repeats in the evolution of the MAL multigene family is discussed.
Mol Gen Genet 1989 May
PMID:Structure of the multigene family of MAL loci in Saccharomyces. 254 70

Using standard growth conditions (LB medium, 37 degrees C, induction with 5 mM IPTG) yeast alpha-glucosidase PI expressed under the control of the regulated tac-hybrid promoter results in the synthesis of insoluble aggregated alpha-glucosidase granules in Escherichia coli. Under these conditions active soluble alpha-glucosidase amounts to less than 1% of the heterologously produced protein. However, the amount of soluble active alpha-glucosidase was dramatically increased when the strong tac-hybrid promoter was to a limited extent induced. This was achieved at concentrations of 0.01 mM IPTG or of 1% lactose or lower in a lactose-permease deficient host strain containing the lacIq repressor gene on an R-plasmid. The formation of active soluble alpha-glucosidase was almost 100% when E. coli cells induced in this manner were cultivated under conditions that reduced growth rate, i.e. at decreased temperature, extreme pH values or in minimal and complete media supplemented with different carbon sources.
Mol Gen Genet 1989 Mar
PMID:Control of formation of active soluble or inactive insoluble baker's yeast alpha-glucosidase PI in Escherichia coli by induction and growth conditions. 265 69

We determined the complete nucleotide sequence of the yeast MAL6R gene from the Saccharomyces carlsbergensis MAL6 locus. The MAL6R gene encodes a transacting protein required for the inducible, coordinate expression of the two divergently transcribed structural genes, MAL6T (maltose permease), and MAL6S (maltase) at this locus. The transcription initiation sites for MAL6R were determined by primer extension experiments. The MAL6R gene contains an open reading frame of 473 amino acids with a calculated Mr of 54,892. The N-terminus of the deduced protein contains an amino acid sequence isologous to a consensus sequence for cysteine-zinc associated DNA binding fingers found in other fungal DNA binding proteins. The MAL6R gene was mapped to chromosome VIII by using OFAGE (orthagonal field alternating gel electrophoresis) gels and hybridization with specific chromosome and MAL6 probes.
Mol Gen Genet 1988 Jul
PMID:Primary structure of the regulatory gene from the MAL6 locus of Saccharomyces carlsbergensis. 285 10

The effects of hydrocortisone and insulin on the intestinal brush border membrane enzymatic activities in an anuran amphibian, Alytes obstetricans, were investigated at the end of spontaneous metamorphosis and 2 weeks after its completion. At the end of metamorphosis, the brush border is differentiating in the apical region of a developing neoformed epithelium. Two weeks after the completion of metamorphosis, this epithelium is entirely formed. The animals received one hormone injection per day for 2 or 3 days running (hydrocortisone: 1, 5, or 25 micrograms/g body wt/day; insulin: 0.5, 1, or 5 mU/g body wt/day). The hydrolases studied were three glucosidases (maltase, glucoamylase, trehalase), gamma-glutamyl-transferase and alkaline phosphatase. In animals reaching the end of metamorphosis, hormonal treatments rarely modify the three glucosidase activities. Two weeks after metamorphosis, a 5 microgram/g body wt/day hydrocortisone injection usually results in a significant increase of the three glucosidase activities. Conversely, a 0.5 mU/g body wt/day insulin injection induced a marked decrease in these activities. At the end of metamorphosis, hydrocortisone has variable effects on gamma-glutamyl-transferase activity; insulin, however, does not significantly modify this activity. Two weeks later, insulin and sometimes hydrocortisone inhibit gamma-glutamyl-transferase activity. Whatever the developmental stage is, hydrocortisone is able to stimulate alkaline phosphatase activity. At the end of metamorphosis, insulin has no influence on this activity, but 2 weeks after metamorphosis, low doses of the hormone (0.5 mU/g body wt/day) significantly reduce it. These results emphasize the possibility that after spontaneous metamorphosis the enzymatic activities of the new intestinal brush border are hormone controlled. This control could be related to the development of the interrenal and pancreatic islet functions.
Gen Comp Endocrinol 1986 Jan
PMID:Hormonal control of the intestinal brush border enzyme activities in developing anuran amphibians. I. Effects of hydrocortisone and insulin during and after spontaneous metamorphosis. 286 4

We have physically and functionally identified three genes at the MAL6 locus of Saccharomyces carlsbergensis. Using multicopy yeast plasmid vectors, we have subcloned various segments of the entire MAL6 locus. The functional characterization of the MAL6 subcloned regions was determined by (1) analyzing biochemically the levels of MAL-encoded proteins (maltase [alpha-D-glucosidase, E.C. 3.2.1.20] and maltose transport protein) in cells transformed with various MAL6 subclones, and (2) testing the ability of the subclones to complement the maltose fermentation defects of well characterized Mal- mutants in the highly homologous MAL1 locus. The physical homology between MAL6 and MAL1 is in part demonstrated by the gene disruption of MAL1 using subcloned MAL6 DNA sequences. The results demonstrate that the MAL6 locus is a complex of at least three genes: MAL6R, MAL6T and MAL6S. These genes specify, respectively, a regulatory function, a maltose transport activity (presumably the maltose permease) and the structural gene for maltase. The functional organization of the MAL6 locus is thus identical to that which we had previously determined by mutational analysis for the MAL1 locus.
Mol Gen Genet 1985
PMID:Organization of the MAL loci of Saccharomyces. Physical identification and functional characterization of three genes at the MAL6 locus. 299 4


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