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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Globin mRNA isolated from rabbit reticulocytes showed an unusually high molecular weight for the beta-chain mRNA (280000 daltons), a large difference between the molecular weight of the alpha-chain mRNA (230000 daltons) and the beta-chain mRNA and a dense and compact structure in the electron microscope (average length of the molecules 0.14 micron), which can be transformed to a linear structure (average length of the molecules 0.44 micron corresponding to a molecular weight of about 420000 daltons). The poly(A)-tail of the mRNA estimated by polyacrylamide gel electrophoresis with poly(A)-markers as reference substances has a size between 12 and 52 nucleotides. The mRNA works as a good template in the cDNA-synthesis with reverse transcriptase and full length copies of the mRNA were obtained by this reaction. The cDNA hybridizes to an amount of 70% with the globin mRNA at a 1:4 cDNA/mRNA ratio.
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PMID:Some unusual properties of globin-mRNA isolated from rabbit reticulocytes. 59 57

We have developed a highly efficient new method for the amplification of alpha- and beta-chain human T-cell receptor (TCR) cDNAs. This method is designated non-palindromic adaptor polymerase chain reaction (NPA-PCR). cDNA was synthesized from total RNA isolated from mononuclear leucocytes, using either an oligo (dT)15-NotI or a C alpha-NotI or a C beta-NotI primer and RNase H-negative reverse transcriptase. The double-stranded cDNA was ligated with the non-palindromic adaptors EcoRI-XmnI [d(ATTCGAACCCCTTCG)] and XmnI G strand [d(pCGAAGGGGTTCG)] (phosphorylated), which resulted in the addition of the EcoRI-XmnI site in both 5' and 3' ends. These two non-palindromic adaptors, EcoRI-XmnI and XmnI G strand, are complementary to each other and both are required for ligation. The EcoRI-XmnI adaptor was removed from the 3' end by treatment with NotI restriction nuclease, whereas it was retained at the 5' end. The non-palindromic adaptor EcoRI-XmnI was used as the 5' amplification primer. C alpha or C beta constant region primers were used as 3' amplification primers. The amplified cDNAs were cloned and the plasmids were used to transform DH5 alpha competent cells. Over 1000 white colonies per 0.1-0.25 micrograms of total RNA or per 10,000 to 50,000 human peripheral blood mononuclear cells were obtained after amplification of either the alpha- or the beta-chain TCR cDNAs. Between 40 and 62% of the colonies (range from five donors) were positive after screening with either a C alpha or a C beta probe, located 5' to the C alpha and C beta amplification primers. A total of 50 amplified alpha- or beta-chain cDNA positive clones from two normal donors were randomly chosen and sequenced, and the sequences obtained were typical of alpha beta TCR. Two new J alpha gene segments were identified. Approximately 30% of the alpha-chain positive clones have 5' untranslated region, and most of the remaining alpha- or beta-chain TCR clones started from the initiation codon or near the 5' end. NPA-PCR has several advantages over existing PCR methods for the amplification of cDNAs with unknown or variable 5' end, such as the T-cell antigen receptors and the immunoglobulins. Among these advantages is that only one 5' end extension primer is required. Because of the large number of TCR V alpha and V beta families, a large number of different 5' end primers are required for amplification of alpha beta TCR cDNAs by conventional PCR.
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PMID:Development of the non-palindromic adaptor polymerase chain reaction (NPA-PCR) for the amplification of alpha- and beta-chain T-cell receptor cDNAs. 134 68

Lamprey liver mRNA sequences were amplified by reverse transcriptase-polymerase chain reaction using primers synthesized according to the amino acid sequences at the thioester region common to the mammalian C3, C4, and alpha 2-macroglobulin (alpha 2M). Two different cDNA species were identified that showed a close similarity to the mammalian C3 or alpha 2M sequences, respectively. Using the C3-like sequence as a probe, two overlapping cDNA clones were isolated from the lambda ZAP library, which together covered the entire region encoding the putative lamprey pro-C3. The deduced amino acid sequence of the putative lamprey pro-C3 contained 1660 amino acids and showed 31%, 22%, 23%, and 16% amino acid sequence identity with mouse C3, C4, C5, and human alpha 2M, respectively. The distributions of cysteine residues were completely identical between the mouse C3 and the putative lamprey C3 except that the lamprey sequence had two additional cysteine residues in the alpha-chain. The possible beta-alpha and alpha-gamma processing sites were found at exactly the same positions as in mammalian C4. These results suggest that the putative lamprey C3 retains a close similarity to the common ancestor of the mammalian C3 and C4, which appeared to have had a three-subunit chain structure.
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PMID:Complete complementary DNA sequence of the third component of complement of lamprey. Implication for the evolution of thioester containing proteins. 157 50

A hybridization assay procedure was devised that makes possible quantitation of the ratio of mRNA of alpha to mRNA of beta globin chains in an RNA sample. The assay uses the radioactive synthetic DNA copies obtained by incubation of RNA-dependent DNA polymerase of avian myeloblastosis virus with rabbit globin mRNA that is 80-90% enriched in mRNA specific for synthesis of alpha or beta globin chains. The rabbit alpha-chain mRNA is obtained from the postribosomal supernatant of rabbit reticulocyte lysates; the rabbit beta-chain mRNA is obtained from the largest polysomes of rabbit reticulocytes treated with L-O-methylthreonine. Sufficient homology exists between rabbit and human globin chains and globin mRNAs that the synthetic DNA copies of chain-specific rabbit globin mRNA hybridize with human globin mRNA. Applied to the study of globin mRNA isolated from reticulocytes of humans with alpha and beta thalassemia, the technique revealed marked quantitative deficiency of alpha-chain mRNA relative to beta-chain mRNA in alpha thalassemia and similar deficiency of beta-chain mRNA relative to alpha-chain mRNA in beta thalassemia. The thalassemia syndromes are therefore characterized by true quantitative deficiency of the mRNA specific for the affected globin chain.
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PMID:Quantitative deficiency of chain-specific globin messenger ribonucleic acids in the thalassemia syndromes. 412 5

Intestinal epithelial cells of the neonatal rat and mouse have been shown to express a major histocompatibility complex (MHC) class I-like Fc receptor, or FcRn, which transports IgG in an apical to basolateral direction. Previous studies have suggested the possible expression of this receptor beyond the neonatal period within the liver. Since bile contains high levels of IgG, we sought to determine whether the FcRn was functionally expressed by adult rat hepatocytes. Using primers specific for FcRn, which did not cross hybridize with MHC class I transcripts, FcRn DNA was amplified by reverse transcriptase polymerase chain reaction from RNA of adult rat hepatocytes. This RNA contained functional FcRn transcripts as it encoded a beta 2-microglobulin-associated cell surface protein as determined by immunoprecipitation of biotinylated cell surface proteins with a polyclonal anti-FcRn specific antiserum. Western blotting of hepatocyte canalicular (apical) and sinusoidal (basolateral) plasma membranes with an FcRn-specific monoclonal antibody further confirmed the protein expression and suggested that FcRn was enriched on the canalicular surface membranes. FcRn, on the surface of hepatocytes, was biologically functional as it bound Fc fragments of IgG at pH 6.0 but not 8.0, which is the same pH dependence observed for FcRn in rat neonatal enterocytes. Thus, FcRn is functionally expressed outside of the neonatal period on the canalicular cell surface of adult hepatocytes. This suggests that hepatocyte FcRn may bind luminal IgG, providing a potential functional communication between parenchymal immune cells and bile.
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PMID:A major histocompatibility complex class I-related Fc receptor for IgG on rat hepatocytes. 773 3

We have recently demonstrated that rat cytomegalovirus (RCMV) infection induces an early inflammatory response in the adventitia (perivasculitis) and in the subendothelial space (endothelialitis) as well as doubles smooth muscle cell (SMC) proliferation and intimal thickening of rat aortic allografts performed from the DA (AG-B4, RT1a) to the WF (AG-B2, RT1v) strain. In this study, the impact of RCMV infection on the structure of inflammation in the allograft adventitia and on the expression of SMC growth factors in the allograft vascular wall was investigated. The recipient rats were inoculated with 10(5) plaque-forming U of RCMV Maastricht strain or left noninfected and used as controls. The allografts were removed at 7 days and 1 and 3 months after transplantation and processed for morphometry and immunohistochemistry. RNA was isolated for reverse transcriptase polymerase chain reaction (RT-PCR). RCMV infection was associated with significantly upregulated presence (P < .05) of T helper (W3/25), T cytotoxic (OX8), and natural killer (3.2.3) cells in the allograft adventitia 7 days after transplantation but not thereafter. More monocyte/macrophages (OX42) were also present in RCMV-infected allografts, but the difference was not significant. Concomitantly, RCMV infection significantly enhanced (P < .05) the expression of major histocompatibility complex class II (OX6) and almost doubled (P = NS) the expression of interleukin-2R (CD25), intercellular adhesion molecule-1 (CD54;1A29), and lymphocyte function-associated antigen-1 alpha-chain (CD11a; WT.1) in the adventitial inflammatory infiltrate. RCMV infection was linked with an early, prominent expression of both PDGF-BB mRNA at 7 days (P < .05) and at 1 month (P < .025) and of transforming growth factor-beta 1 mRNA at 7 days (P < .025) and at 1 month (P < .025) after transplantation. A less-prominent mRNA upregulation of acidic fibroblast growth factor (P < .05) was associated with RCMV infection at 7 days and at 1 month, as well as of epidermal growth factor at 1 month after transplantation, when compared with noninfected allografts, although the mRNA expression in both groups was below the levels of nontransplanted DA aortas. RCMV infection almost doubled basic fibroblast growth factor mRNA expression (P = NS) in the allograft vascular wall at 7 days and at 1 month. RCMV infection had no additional impact on insulin-like growth factor-1 mRNA expression when compared with noninfected allografts.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Cytomegalovirus infection enhances mRNA expression of platelet-derived growth factor-BB and transforming growth factor-beta 1 in rat aortic allografts. Possible mechanism for cytomegalovirus-enhanced graft arteriosclerosis. 798 Nov 94

DAB486IL-2 is a recombinant toxin with the cell surface-binding domain of diphtheria toxin (DT) replaced by interleukin-2 (IL-2). To correlate clinical response with expression of components of the IL-2 receptor (IL-2R), 14 patients with cutaneous T-cell lymphoma (CTCL) received five daily 90-minute infusions every 21 days. There were no complete responses, 1 partial response (PR), 2 major biologic effects (major cutaneous improvement without change in circulating neoplastic cells), 3 stable disease (SD), and 8 progressive disease (PD). Responders had easily detected expression of CD25 (Tac; alpha-chain of IL-2R) in skin, and in two responders expression of the beta chain of the IL-2 receptor (beta-IL-2R) was detectable by reverse transcriptase-polymerase chain reaction. CD25 was also detected in 8 of 11 SD or PD patients, with beta-IL-2R in 3 of 8 SD or PD patients. Two of the three responders had anti-DT antibodies before treatment. Reversible increased hepatic transaminases occurred in 13 of 14 patients during the first course, with decreased frequency in repeated courses. The maximal serum concentration after the first infusion of DAB486IL-2 varied (1,369 +/- 1,155 ng/mL [mean +/- SD]; n = 14; range, 55 to 3,999 ng/mL) with a short half-life (T1/2 beta = 0.21 +/- 0.12 h [mean +/- SD]; range, 0.099 to 0.57 h). The area under the concentration curve varied inversely with anti-DT antibody titer. We conclude that DA-B486IL-2 has valuable activity in certain patients with CTCL. Expression of the IL-2R may be necessary but is not sufficient to predict response.
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PMID:Chimeric fusion protein toxin DAB486IL-2 in advanced mycosis fungoides and the Sezary syndrome: correlation of activity and interleukin-2 receptor expression in a phase II study. 808 Sep 84

A feline large granular lymphocyte (LGL) cell line was established from a cat with an alimentary-form lymphoma. This cell line, designated as FGL, had many large azurophilic granules in the cytoplasm, which were typical to LGL cells. Proviral genome of feline leukemia virus was detected in the chromosomal DNA of FGL cells, and reverse transcriptase activity was also demonstrated in the culture supernatant. Furthermore, we found expression of interleukin 2 (IL-2) receptor alpha-chain on the cell surface of FGL and its natural killer activity against human erythroblastic leukemia cell line, K562.
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PMID:Establishment and characterization of a feline large granular lymphoma cell line expressing interleukin 2 receptor alpha-chain. 828 47

Highly purified progenitors (including erythroid [BFU-E], granulo-monocytic [CFU-GM], multipotent [CFU-GEMM] progenitors, as well as multipotent progenitors with self-renewal capacity [CFU-B]) express high-affinity growth factor receptors (GFRs), with prevalent interleukin-3 receptors (IL-3Rs) (2,700/cell), a > or = 10-fold lower number of IL-6Rs (145/cell) and granulocyte-macrophage colony-stimulating factor receptors (GM-CSFRs) (300/cell), and a barely detectable level of erythropoietin (Ep) receptors (75/cell). Hematopoietic growth factor (HGF) dosages inducing peak clonogenetic effects are associated with partial/subtotal occupancy of the homologous HGF receptor (HGFR). Cross-reactivity between GFRs and heterologous GFs (including IL-6, IL-3, GM-CSF, Ep, and the kit ligand [KL]) was explored by competition experiments on purified progenitors with radiolabeled and excess cold HGFs at +4 degrees C. No cross-reaction was observed between IL-6R, IL-3R, EpR, and the heterologous GFs, whereas the GM-CSFR showed cross-reactivity with IL-3 and, to a lesser extent, KL. Modulation of GFRs was examined after 18 or 40 hours of incubation with GF(s) at 37 degrees C, followed by ligand-binding assay at 20 degrees C. IL-6, IL-3, GM-CSF, and Ep induce a marked down-modulation of their own receptors. Interestingly, each GF induces the transactivation of the R(s) for the "distal" GF(s): (1) IL-6 induces transactivation of IL-3R, but not of GM-CSFR/EpR; (2) IL-3 causes a rapid upmodulation of GM-CSFR/EpR ("pure" progenitors treated with IL-3 show upmodulation of GM-CSFR alpha-chain mRNA by reverse transcriptase-polymerase chain reaction); whereas (3) GM-CSF induces the transactivation of the EpR. This chain upmodulation of HGFRs may underlie the synergistic interactions between the HGFs in clonogenetic culture. It is emphasized that KL does not induce upmodulation of the other GFRs. Finally, Ep, GM-CSF, and IL-3 do not modulate the expression of the "proximal" HGFRs (ie, GM-CSFR/IL-3R/IL-6R, IL-3R/IL-6R, and IL-6R, respectively). These results allow insight into the cellular basis of hematopoiesis, ie, the complex and coordinate interactions between HGFs and their receptors. They are compatible with a model of cascade transactivation via upmodulation of GFRs in the initial key steps of hematopoietic differentiation, whereby the action of each GF enhances the effect of the distal GF(s) by a multistep chain-potentiation mechanism.
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PMID:Cascade transactivation of growth factor receptors in early human hematopoiesis. 845 93

Interleukin-15 (IL-15) shares many biological functions with interleukin-2 (IL-2) due to common receptor components. IL-15 binds to the IL-2 receptor (IL-2R) beta-chain and the common gamma-chain receptor in addition to one other IL-15 binding receptor protein (IL-15R alpha). Both IL-2R beta- and gamma-chains are required to promote cell growth in hematopoietic cells. The colonic cryptlike epithelial cell line T84 contains the common gamma-chain but lacks the IL-2R beta-chain. We report IL-15R alpha-chain mRNA in T84 cells with the use of reverse transcriptase-polymerase chain reaction. T84 and normal colonic epithelial cells bind a FLAG-IL-15 fusion protein in immunoperoxidase and flow cytometric experiments. In addition, IL-15, but not IL-2, accelerates and enhances the development of transepithelial resistance across T84 monolayers in a dose-dependent fashion. We conclude that normal and T84 colonic epithelial cells express IL-15R alpha and are able to bind IL-15. IL-15 can deliver a nonproliferative functional signal in the absence of IL-2R beta-chain in T84 cells.
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PMID:Interleukin-15 signals T84 colonic epithelial cells in the absence of the interleukin-2 receptor beta-chain. 917 31


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