Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 5-kDa polypeptide, pseudothionin Solanum tuberosum 1 (Pth-St1), which was active against Clavibacter michiganensis subspecies sepedonicus, a bacterial pathogen of potatoes, has been purified from the buffer-insoluble fraction of potato tubers by salt extraction and HPCL. Pth-St1 was also active against other potato pathogens tested (Pseudomonas solanacearum and Fusarium solani). The N-terminal amino acid sequence of this peptide was identical (except for a N/H substitution at position 2) to that deduced from a previously reported cDNA sequence (EMBL accession number X-13180), which had been misclassified as a Browman-Birk protease inhibitor. Pth-St1 did not inhibit either trypsin or insect alpha-amylase activities, and, in contrast with true thionins, did not affect cell-free protein synthesis or beta-glucuronidase activity. Northern-blot and tissue-print analyses showed that steady-state mRNA levels were highest in flowers (especially in petals), followed by tubers (especially in the epidermal cell layers and in leaf primordia), stems and leaves. Infection of leaves with a bacterial pathogen suspended in 10 mM MgCl2 switched off the gene, whereas mock inoculation with 10 mM MgCl2 alone induced higher mRNA levels.
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PMID:Pseudothionin-St1, a potato peptide active against potato pathogens. 803 86

With the use of an enzyme-linked immunosorbent assay (ELISA), it was revealed that surface antigens of both adult and fourth-stage larvae (L4) of Ostertagia circumcincta induced high levels of serum IgG antibodies, while serum IgA antibody levels were low but increased significantly (P < 0.01) after infection. Immunofluorescence studies on the surface of viable L4 and adult nematodes showed that the IgG response was stage-specific only in animals vaccinated with adult surface extracts. The results of Western blot analysis using these antibodies suggested that at least eight polypeptides were shed from the L4 surface to the environment and that infection induced (or boosted) IgG antibody against a further four polypeptides. A comparison of reactivity of pre- and post-infection sera of sheep vaccinated with adult nematode surface antigens suggested that only one of the antigens stripped from the nematode surface was immunogenic and/or present in a concentration sufficient to induce an IgG response following parenteral vaccination. Infection boosted the IgG antibodies to a further four polypeptides. Only one polypeptide of 63 kDa seems to be shed in vivo from the adult nematode surface. Ten to eleven antigens were recognised in adult excretory/secretory products by serum IgG of multiple-infected sheep.
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PMID:Surface and excretory/secretory antigens of fourth-stage larvae and adult Ostertagia circumcincta. 809 9

The ability of Leishmania mexicana amazonensis to inhibit antigen specific T-cell proliferation against a non-parasite polypeptide antigen, poly(LTyr, LGlu)-poly(DLAla)--poly(LLys), was examined. Infection of mouse peritoneal macrophages by promastigotes blocked the proliferation of the T-cell line, TPB1. This effect was correlated with the level of parasite infection, and the timing of macrophage infection and antigen addition. Peritoneal macrophages from both BALB/b and C57BL/6 mice showed reduced ability to serve as antigen presenting cells.
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PMID:Effect of macrophage infection by Leishmania on the proliferation of an antigen-specific T-cell line, TPB1, to a non-parasite antigen. 823 64

Infection of Nicotiana clevelandii protoplasts by raspberry ringspot nepovirus resulted in the accumulation of about 24 polypeptides that differed in M(r) and pI from polypeptides accumulating in mock-inoculated protoplasts. Similar polypeptides accumulated in protoplasts infected with the S and E strains of RRV but different infection-specific polypeptides were detected in protoplasts infected with tobacco ringspot nepovirus. The M(r) of RRV-specific polypeptides ranged from 210,000 to 18,000 and most are presumed to be derived from others by proteolytic cleavage. No evidence was found for marked changes in polypeptide abundance with time after inoculation or for any virus-specific polypeptide becoming disproportionately abundant in the medium during culture.
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PMID:Polypeptide synthesis induced in Nicotiana clevelandii protoplasts by infection with raspberry ringspot nepovirus. 847 Sep 49

To investigate the regulation of the Na,K-ATPase, we have studied the expression of the Na,K-ATPase polypeptides in several mammalian cell lines using the vaccinia virus/T7 RNA polymerase expression system. Infection of several fibroblast-like cell lines with viral recombinants containing the Na,K-ATPase alpha and beta isoforms, the glucose transporters, GLUT 1 and GLUT 4, or the capsid protein of the Sindbis virus all result in the production of the appropriate protein products. However, all epithelial cell lines tested fail to synthesize the Na,K-ATPase viral recombinants, yet they efficiently express the other virally directed polypeptides. While Madin-Darby canine kidney (MDCK) epithelial cells infected with the Na,K-ATPase alpha1 or beta1 recombinant viruses produce both mRNAs, the messages are inefficiently translated. Furthermore, the RNA from infected MDCK cells does not direct the in vitro synthesis of the beta1 polypeptide, whereas the message from infected fibroblast-like BSC 40 cells is efficiently translated both in vivo and in vitro. Moreover, the synthesis of the H,K-ATPase alpha subunit is also limited in MDCK cells, although the H,K-ATPase beta subunit is efficiently expressed. Expression of chimeras constructed between the Na+ pump beta1 isoform and the H,K-ATPase beta subunit indicates that sequences in the 5' coding region of the beta1 message have an inhibitory effect; however, the stringent translational regulation of the beta1 isoform in MDCK cells requires the 5' and 3' regions of the coding sequence. The ability of the polarized cell lines to limit the synthesis of the Na+ pump polypeptides while expressing other vaccinia recombinants at high levels suggests that the polarized cells possess a stringent mechanism for the specific translational regulation of a select set of messages.
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PMID:Translational regulation of Na,K-ATPase alpha1 and beta1 polypeptide expression in epithelial cells. 879 17

Infection with some virus types induces susceptibility to the cytotoxic effect of tumor necrosis factor alpha (TNF-alpha). To investigate whether expression of polyomavirus proteins has this effect on cells, the TNF-alpha sensitivity of C127 and L929 mouse cells transfected with viral DNA was analyzed. Expression of all three polyomavirus early proteins, the tumor (T) antigens, had no apparent effect. In contrast, middle T antigen by itself induced hypersensitivity to TNF-alpha. This effect was reversed by retransfection of the cells with DNA encoding small T antigen. Expression of this polypeptide also decreased the sensitivity of bovine papillomavirus type 1-transformed cells to TNF-alpha, showing that the protective function of the polyomavirus small T antigen was not strictly linked to a middle-T-antigen-induced event. Mouse and human TNF-alpha had the same effect on normal and transformed mouse cells, suggesting that this effect was mediated by TNF receptor 1. Consistent with this conclusion, all cell clones used in the experiments expressed TNF receptor 1 at similar levels, while we failed to detect TNF receptor 2. The amount of receptor on the cells was not influenced by binding of the ligand. Addition of TNF-alpha at cytotoxic concentrations to cells expressing middle T antigen by itself resulted in significant fragmentation of chromosomal DNA after only a few hours, indicating induction of apoptosis. Addition of the cytokine to these cells also leads to release of arachidonic acid, showing that phospholipase A2 was activated. However, production of arachidonic acid did not appear to significantly precede loss of cell viability.
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PMID:Altered susceptibility to tumor necrosis factor alpha-induced apoptosis of mouse cells expressing polyomavirus middle and small T antigens. 898 47

Heat shock proteins (HSP) in the size range of M(r) 60,000 are major targets of the immune response in vivo. The leishmania heat-inducible proteins of M(r) 65-67,000 are expressed at relatively high levels in infected macrophages (Infection and Immunity 1993, 61, 3265-3272) and may be important targets of the host response. To facilitate further studies concerned with these proteins, the HSP60 gene of Leishmania major was cloned, sequenced, and expressed. A lambdaEMBL-3 L. major genomic library was screened with a PCR-generated DNA probe derived from a highly conserved region of the leishmania HSP60 gene. A single clone that hybridized strongly was characterized. Sequence analysis revealed an open reading frame of 1770 bp encoding a putative polypeptide of 589 amino acids with a predicted size of M(r) 64,790 and with the highest degree of amino acid sequence similarity (56%) to HSP60 from Trypanosoma cruzi. Less extensive amino acid sequence similarity (48%) was observed between that leishmania HSP60 and the corresponding human protein. Notably, significant regions of sequence dissimilarity between the leishmania and human proteins were identified principally within the carboxy-terminal regions of the proteins. The entire coding region of the leishmania HSP60 gene was subcloned into the pET-3a vector and expressed in Escherichia coli. Purified recombinant protein was used to examine sera from patients with tegumentary leishmaniasis from Colombia for the presence of antibodies to HSP60. Unlike sera from healthy, uninfected controls, sera from patients reacted strongly with recombinant leishmania HSP60. This recognition had specificity in that these same sera showed little or no reactivity with either recombinant mycobacterial HSP65 or recombinant human HSP60. These findings indicate that patients with tegumentary forms of leishmaniasis have humoral responses to leishmania HSP60. Further studies of this protein will clarify its importance as a target of the immune response and as a potential antigen for serodiagnosis.
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PMID:Leishmania major: molecular cloning, sequencing, and expression of the heat shock protein 60 gene reveals unique carboxy terminal peptide sequences. 908 22

An epidemiologic association between viral infections and the onset of asthma and allergy has been documented. Also, evidence from animal and human studies has suggested an increase in antigen-specific immunoglobulin E (IgE) production during viral infections, and elevated levels of IgE are characteristic of human asthma and allergy. Here, we provide molecular evidence for the roles of viral infection and of activation of the antiviral protein kinase (PKR) (double-stranded-RNA [dsRNA]-activated protein kinase) in the induction of IgE class switching. The presence of dsRNA, a known component of viral infection and an activator of PKR, induced IgE class switching as detected by the expression of germ line epsilon in the human Ramos B-cell line. Furthermore, dsRNA treatment of Ramos cells resulted in the activation of PKR and in vivo activation of the NF-kappaB complex. Interestingly, infection of Ramos cells with rhinovirus (common cold virus) serotypes 14 and 16 resulted in the induction of germ line epsilon expression. To further evaluate the role of PKR in the viral induction of IgE class switching, we infected Ramos cells with two different vaccinia virus (cowpox virus) strains. Infection with wild-type vaccinia virus failed to induce germ line epsilon expression; however, a deletion mutant of vaccinia virus (VP1080) lacking the PKR-inhibitory polypeptide E3L induced the expression of germ line epsilon. Collectively, the results of our study define a common molecular mechanism underlying the role of viral infections in IgE class switching and subsequent induction of IgE-mediated disorders such as allergy and asthma.
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PMID:Activation of antiviral protein kinase leads to immunoglobulin E class switching in human B cells. 944 15

Glycine is an essential co-agonist of the excitatory N-methyl-D-aspartate (NMDA) receptor, a subtype of the ionotropic glutamate receptor family. The glycine binding site of this hetero-oligomeric ion channel protein is formed by two distinct extracellular regions, S1 and S2, of the NR1 subunit, whereas the homologous domains of the NR2 subunit mediate glutamate binding. Here, segments S1 and S2 of the NR1 polypeptide were fused via a linker peptide followed by N- and C-terminally tagging with Flag and His6 epitopes, respectively. Infection of High Five insect cells with a recombinant baculovirus containing this glycine binding site construct resulted in efficient secretion of a soluble fusion protein of about 53 kDa. After affinity purification to near-homogeneity, the fusion protein bound the competitive glycine site antagonist [3H]MDL105,519 with high affinity (Kd = 5.22 +/- 0. 13 nM) similar to that determined with rat brain membrane fractions. This high affinity binding could be competed by the glycine site antagonist 7-chlorokynurenic acid as well as the agonists glycine and D-serine but not by L-glutamate. This indicates that the S1 and S2 domains of the NR1 subunit are sufficient for the formation of a glycine binding site that displays pharmacological properties similar to those of the NMDA receptor in vivo.
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PMID:Expression and initial characterization of a soluble glycine binding domain of the N-methyl-D-aspartate receptor NR1 subunit. 968 27

With the aim of developing transmission-blocking vaccines based on the sexual stage-specific surface antigen Pfs48/45 of the human malaria parasite Plasmodium falciparum, the gene encoding Pfs48/45 was incorporated into the genome of a recombinant vaccinia virus. In virus-infected mammalian tissue culture cells, recombinant Pfs48/45 antigen (rPfs48/45) is posttranslational modified to produce a highly N-glycosylated polypeptide. The rPfs48/45 protein was radiolabeled with ethanolamine, consisting of a further posttranslational modification in the form of a glycosylphosphatidylinositol anchor at its carboxy-terminal end. The rPfs48/45 was not detected on the surface of the infected cells; instead, it remained within the secretion pathway of mammalian cells irrespective of the duration of infection or culture temperature. Studies with monoclonal antibodies specific for disulfide band-dependent epitopes of Pfs48/45 revealed that recombinant Pfs48/45 is not folded in its authentic conformation even if N-glycosylation was chemically inhibited. Infection of mice and rabbits with recombinant virus elicited Pfs48/45-specific antibodies; however, the antisera failed to block parasite transmission in a standard mosquito membrane-feeding assay.
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PMID:Plasmodium falciparum: heterologous synthesis of the transmission-blocking vaccine candidate Pfs48/45 in recombinant vaccinia virus-infected cells. 976 46


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