Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two specific beta-N-acetylglucosaminyltransferases involved in the branching and elongation of mucin oligosaccharide chains, namely, a beta 1,6 N-acetylglucosaminylsaminyltransferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal beta 3GalNAc-mucin to yield Gal beta 3(GlcNAc beta 6)GalNAc-Mucin and a beta 3-N-acetylglucosaminyl transferase that transfers N-acetylglucosamine from UDP-N-acetylglucosamine to Gal beta 3(GlcNAc beta 6)GalNAc-mucin to yield GlcNAc beta 3Gal beta 3 (GlcNAc beta 6)GalNAc-Mucin were purified from the microsomal fraction of swine trachea epithelium. The beta 1,6-N-acetylglucosaminyltransferase was purified about 21,800-fold by procedures which included affinity chromatography on DEAE columns containing bound asialo Cowper's gland mucin glycoprotein with Gal beta 1,3GalNAc side chains. The apparent molecular weight estimated by gel filtration was found to be about 60 Kd. The purified enzyme showed a high specificity for Gal beta 1,3GalNAc chains and the most active substrates were mucin glycoproteins containing these chains. The apparent Km of the beta 6-glucosaminyltrans-ferase for Cowper's gland mucin glycoprotein containing Gal beta 1,3GalNAc chains was 0.53 microM; for UDP-N-acetylglucosamine, 12 microM; and for Gal beta 1,3GalNAc alpha NO2 phi, 4 mM. The activity of the beta 6-glucosaminyltransferase was dependent on the extent of glycosylation of the Gal beta 3GalNAc chains in Cowper's gland mucin glycoprotein. The best substrate for the partially purified beta 3-Glucosaminyltransferase was Cowper's gland mucin glycoprotein containing Gal beta 1,3(GlcNAc beta 6)GalNAc side chains. This enzyme showed little or no activity with intact sialylated Cowper's gland mucin glycoprotein or derivatives of this glycoprotein containing GalNAc or Gal beta 1,3GalNAc side chains. The radioactive oligosaccharides formed by these enzymes in large scale reaction mixtures were released from the mucin glycoproteins by treatment with alkaline borohydride, isolated by gel filtration on Bio-Gel P-6 and characterized by methylation analysis and sequential digestion with exoglycosidases. The oligosaccharide products formed by the beta 6- and beta 3-glucosaminyltransferases were shown to be Gal beta 3(GlcNAc beta 6) GalNAc and GlcNAc beta 3 Gal beta 3(GlcNAc beta 6)GalNAc respectively. Taken collectively, these results demonstrate that swine trachea epithelium contains two specific N-acetylglucosaminyltransferases which catalyze the initial branching and elongation reactions involved in the synthesis of O-linked oligosaccharide chains in respiratory mucin glycoproteins. The first enzyme a beta 6-glucosaminyltransferase converts Gal beta 3GalNAc chains in mucin glycoproteins to Gal beta 3(GlcNAc beta 6)GalNAc chains.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Cell Biochem 1991 Mar 13
PMID:UDP-GlcNAc: Gal beta 3GalNAc-mucin: (GlcNAc----GalNAc) beta 6-N-acetylglucosaminyltransferase and UDP-GlcNAc: Gal beta 3(GlcNAc beta 6) GalNAc-mucin (GlcNAc----Gal)beta 3-N-acetylglucosaminyltransferase from swine trachea epithelium. 183 Jun 37

We demonstrate that RNA polymerase bound at the PR promoter of bacteriophage lambda can repress transcription initiation from the divergently transcribed PRM promoter in vitro. Using abortive initiation and run-off transcription experiments we show that inactivating mutations introduced into either the -10 or -35 regions of PR result in a significant increase in the rate of formation of transcriptionally competent complexes at the PRM promoter. This is due primarily to an increase in the rate constant for the isomerization of closed to open complexes. Gel shift and DNase I footprinting experiments were employed to further define the mechanism by which PR sequences mediate PRM repression. From these assays we were able to conclude that the formation of an open complex at the PR promoter did not exclude RNA polymerase from binding at PRM. Rather, initiation at PRM was impaired because closed complexes must isomerize in the presence of an open complex already situated at the PR promoter. Extensive evidence has been obtained previously indicating that lambda repressor activates transcription directly by contacting RNA polymerase situated at the PRM promoter. Results presented here raise the possibility that an additional mechanism could be operative, whereby lambda repressor indirectly activates PRM transcription by excluding RNA polymerase from the PR promoter.
J Mol Biol 1991 Dec 05
PMID:RNA polymerase bound to the PR promoter of bacteriophage lambda inhibits open complex formation at the divergently transcribed PRM promoter. Implications for an indirect mechanism of transcriptional activation by lambda repressor. 183 35

The Ca2+/Mg2+ ATPase, which is activated by millimolar concentrations of Ca2+ or Mg2+, was solubilized from rat heart plasma membrane by employing lysophosphatidylcholine, CHAPS, NaI, EDTA and Tris-HCl at pH 7.4. The enzyme was purified by sucrose density gradient, Affi-Gel Blue column and Sepharose 6B column chromatography. The purified enzyme was seen as a single peptide band in the sodium dodecyl sulfate polyacrylamide gel electrophoresis with a molecular weight of about 90,000. The apparent molecular weight of the holoenzyme as determined under non-dissociating conditions by gel filtration on Sepharose 6B column was about 180,000 indicating two subunits. The enzyme was insensitive to ouabain, verapamil, vanadate, oligomycin, N,N-dicyclohexylcarbodiimide and NaN3, but was markedly inhibited by 20 microM gramicidin S and 50 microM trifluoperazine. Analysis of the purified Ca2+/Mg2+ ATPase revealed the presence of 17 amino acids where leucine, glutamic acid and aspartic acid were the major components and histidine, cysteine and methionine were the minor components. The purified enzyme was associated with 19.7 mumol phospholipid/mg protein which was 60 times higher than the phospholipid content in plasma membrane. The cholesterol content in the purified enzyme preparation was 0.75 mumol/mg protein and this represented an 8-fold enrichment over plasma membrane. The glycoprotein nature of the enzyme was evident from the positive periodic acid-Schiff staining of the purified Ca2+/Mg2+ ATPase in the sodium dodecyl sulfate polyacrylamide gel. The polysaccharide content of the enzyme was enriched 8-fold over plasma membrane; neuraminidase treatment decreased the polysaccharide content. Concanavalin A prevented the ATP-dependent inactivation of the purified Ca2+/Mg2+ ATPase and was found to bind to the purified enzyme with a KD of 576 nM and Bmax of 4.52 nmol/mg protein. The results indicate that Ca2+/Mg2+ ATPase is a glycoprotein and contains a large amount of lipids.
Mol Cell Biochem 1991 Oct 16
PMID:Purification and composition of Ca2+/Mg2+ ATPase from rat heart plasma membrane. 183 89

The gene coding for apolipoprotein AI (apoAI), a plasma protein involved in the transport of cholesterol and other lipids in the plasma, is expressed predominantly in liver and intestine. Previous work in our laboratory has shown that different cis-acting elements in the 5'-flanking region of the human apoAI gene control its expression in human hepatoma (HepG2) and colon carcinoma (Caco-2) cells. Hepatocyte-specific expression is mediated by elements within the -256 to -41 DNA region relative to the apoAI gene transcription start site (+1). In this study it was found that the -222 to -110 apoAI gene region is necessary and sufficient for expression in HepG2 cells. It was also found that this DNA region functions as a powerful hepatocyte-specific transcriptional enhancer. Gel retardation and DNase I protection experiments showed that HepG2 cells contain proteins that bind to specific sites, sites A (-214 to -192), B (-169 to -146), and C (-134 to -119), within this enhancer. Site-directed mutagenesis that prevents binding of these proteins to individual or different combinations of these sites followed by functional analysis of these mutants in HepG2 cells revealed that protein binding to any one of these sites in the absence of binding to the others was not sufficient for expression. Binding to any two of these sites in any combination was sufficient for only low levels of expression. Binding to all three sites was essential for maximal expression. These results indicate that the transcriptional activity of the apoAI gene in liver cells is dependent on synergistic interactions between transcription factors bound to its enhancer.
Mol Cell Biol 1991 Feb
PMID:Synergistic interactions between transcription factors control expression of the apolipoprotein AI gene in liver cells. 184 69

Cytochrome c-oxidase type aa3 (EC 1.9.3.1) was purified to homogeneity from vegetative Bacillus cereus by ion-exchange and hydroxylapatite chromatography in the presence of Triton X-100. Gel filtration analysis suggested a dimeric structure apparently 172 kDa in size; however, only a monomer of 81 kDa was detected when analysed by non-denaturing gel electrophoresis. Denaturing gel electrophoresis analysis of the protein showed the presence of two subunits (51 and 30 kDa). Atomic absorption and visible spectroscopy showed typical aa3 redox centres with haem a iron and copper in a ratio of 22 nmol and 35 ng-atom per mg protein, respectively. No haem c was found associated with the purified enzyme in the conditions reported here. Oxidase activity was fully reconstituted by phospholipids in the presence of N,N,N',N'-tetramethyl-p-phenylenediamine or reduced yeast cytochrome c (but not horse cytochrome c) as electron donors. This activity was abolished by cyanide and carbon monoxide.
Mol Microbiol 1991 Jan
PMID:Purification and characterization of two-subunit cytochrome aa3 from Bacillus cereus. 184 7

The alpha B-crystallin gene is expressed at high levels in lens and at lower levels in some other tissues, notably skeletal and cardiac muscle, kidney, lung, and brain. A promoter fragment of the murine alpha B-crystallin gene extending from positions -661 to +44 and linked to the bacterial chloramphenicol acetyltransferase (CAT) gene showed preferential expression in lens and skeletal muscle in transgenic mice. Transfection experiments revealed that a region between positions -426 and -257 is absolutely required for expression in C2C12 and G8 myotubes, while sequences downstream from position -115 appear to be determinants for lens expression. In association with a heterologous promoter, a -427 to -259 fragment functions as a strong enhancer in C2C12 myotubes and less efficiently in myoblasts and lens. Gel shift and methylation interference studies demonstrated that nuclear proteins from C2C12 myoblasts and myotubes specifically bind to the enhancer.
Mol Cell Biol 1991 Sep
PMID:Expression of the murine alpha B-crystallin gene in lens and skeletal muscle: identification of a muscle-preferred enhancer. 187 25

The second intron of the E beta gene in the mouse major histocompatibility complex is the site of a meiotic recombination hot spot. We detected two DNase I-hypersensitive sites in this intron in meiotic cells isolated from mouse testes. One site appears to be constitutive and is found in other tissues regardless of whether or not they express the E beta gene. Near this hypersensitive site are potential binding motifs for H2TF1/KBF1, NF kappa B, and octamer transcription factors. Gel retardation studies with mouse lymphoma cell nuclear extracts confirmed that each of these motifs is capable of binding protein. The binding of transcription factors may contribute to the enhancement of recombination potential by altering chromatin structure and increasing the accessibility of the DNA to the recombination machinery.
Mol Cell Biol 1991 Apr
PMID:DNase I-hypersensitive sites and transcription factor-binding motifs within the mouse E beta meiotic recombination hot spot. 190 Sep 17

Protein p4 of the Bacillus subtilis phage phi 29 switches on the transcription of the viral late genes by binding to the viral late promoter at a region close to the RNA polymerase binding site. Gel retardation and DNase I footprinting assays show that the presence of protein p4 is required for RNA polymerase recognition of the late promoter. The protein p4 and RNA polymerase DNA binding sites have been separated by the insertion of bent and non-bent DNA sequences of different lengths. These mutant promoters were used to study in vitro their protein p4-dependent transcriptional activity and their interaction with both protein p4 and RNA polymerase. The results indicate that protein p4 is able to function at longer DNA distances from the RNA polymerase binding site than in the natural promoter. The extent of protein p4 activity depended on the length and conformation of the inserted DNA. Activation of transcription and RNA polymerase binding was favoured when the relative orientation of protein p4 and RNA polymerase was conserved and when the intervening DNA had a bent conformation. These data, together with the DNase I footprints, suggest that activation at distance by protein p4 involves a DNA loop held by the interaction of protein p4 and RNA polymerase.
J Mol Biol 1991 Jun 05
PMID:Transcription activation at a distance by phage phi 29 protein p4. Effect of bent and non-bent intervening DNA sequences. 190 41

The second enhancer (enhancer II) of hepatitis B virus is functionally liver specific. Located within an open reading frame of the virus and immediately upstream of the initiation sites of viral major transcripts, enhancer II furnishes a unique model for use in investigating the structure and function of an enhancer. In this study, two functional constituents, a 23-bp box-alpha and a 12-bp box-beta, are identified as being both necessary and sufficient for enhancer II function. Examination of the box-alpha and box-beta sequences reveals a weak homology to the extended consensus for a C/EBP binding site. Gel shift and footprinting analyses indicate that multiple proteins bind to these sequences and thus are candidate transcription factors that mediate the enhancer function. One heat-resistant protein, protein a, and one heat-sensitive protein, protein b, bind to box-alpha. Protein a, which binds to box-alpha in a way indistinguishable from that seen with a recombinant C/EBP, appears not to be identical to C/EBP in that the binding of protein a requires a minimal sequence larger than the canonical C/EBP sites. Two box-beta-binding proteins, c and d, show greater affinity for the C/EBP consensus than for box-beta. However, both proteins c and d are relatively heat sensitive and display a distinct sequence preference from the recombinant C/EBP protein. Since the function of enhancer II is strictly dependent on a bipartite architecture, this system provides a unique model for studies of how the interactions of its binding proteins lead to the enhancer function.
Mol Cell Biol 1991 Oct
PMID:C/EBP-like proteins binding to the functional box-alpha and box-beta of the second enhancer of hepatitis B virus. 192 32

The maize rab17 gene is expressed in different plant parts in response to ABA and osmotic stress (J. Vilardell et al., Plant Mol Biol 14 (1990) 423-432). Here we demonstrate that 5' upstream sequences of the rab17 gene confer the appropriate patterns of expression on the chloramphenicol acetyl transferase (CAT) reporter gene in transgenic tobacco plants, as well as in protoplasts derived from cultured rice cells. Specifically, a CAT construct containing a large 5' upstream fragment of rab17 (-1330/+29) results in high levels of CAT activity in embryos, leaves and roots of transgenic plants subjected to water stress or ABA treatment. Transient expression assays in rice protoplasts transfected with CAT genes fused to rab17 promoter deletions indicate that a 300 bp DNA fragment (-351/-102) is sufficient to confer ABA responsiveness upon the reporter gene. Furthermore, a 100 bp sequence (-219/-102) is capable of conferring ABA responsiveness upon a minimal promoter derived from the 35S CaMV promoter. Gel retardation experiments indicate that maize nuclear proteins bind to this fragment. This region of 100 bp contains a sequence (ACGTGGC) which has been identified as an abscisic acid response element in studies of other ABA-responsive plant genes.
Plant Mol Biol 1991 Nov
PMID:Regulation of the maize rab17 gene promoter in transgenic heterologous systems. 193 88


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>