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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have identified Celsr1, a gene that encodes a developmentally regulated vertebrate seven-pass transmembrane protein. The extracellular domain of Celsr1 contains two regions each with homology to distinct classes of well-characterized motifs found in the extra-cellular domains of many cell surface molecules. The most N-terminal region contains a block of contiguous cadherin repeats, and C-terminal to this is a region containing seven epidermal growth factor-like repeats interrupted by two laminin A G-type repeats. Celsr1 is unique in that it contains this combination of repeats coupled to a seven-pass transmembrane domain. As part of the characterization of the Celsr1 gene, we have determined its chromosomal map location in both mouse and human. The European Collaborative Interspecific Backcross (EUCIB) and BXD recombinant inbred strains were used for mapping Celsr1 cDNA clones in the mouse, and fluorescence in situ hybridization was used to map human Celsr1 cosmid clones on metaphase chromosomes. We report that Celsr1 maps to proximal mouse Chromosome 15 and human chromosome 22qter, a region of conserved synteny. Reverse transcriptase-polymerase chain reaction analysis and in situ hybridization were used to determine the spatial restriction of Celsr1 transcripts in adult and embryonic mice. The results presented here extend our previous finding of expression of the Celsr1 receptor in the embryo and show that expression continues into adult life when expression in the brain is localized principally in the ependymal cell layer, choroid plexus, and the area postrema.
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PMID:Celsr1, a neural-specific gene encoding an unusual seven-pass transmembrane receptor, maps to mouse chromosome 15 and human chromosome 22qter. 933 65

The transmembrane protein tissue factor (TF) is the cell surface receptor for coagulation factor VII (FVII) and activated factor VII (FVIIa). Recently, TF has been identified as a regulator of angiogenesis, tumor growth, and metastasis. This study was designed to link the binding of FVII(a) to its receptor, TF, with the subsequent triggering of angiogenesis through vascular endothelial growth factor (VEGF) production by human lung fibroblasts. We report that incubation of fibroblasts, which express constitutive surface TF, with FVII(a) induces VEGF synthesis. FVII(a)-induced VEGF secretion, assessed by a specific enzyme-linked immunosorbent assay, was time- and concentration-dependent. VEGF secretion was maximal after 24 hours of incubation of the cells with 100 nmol/L FVII(a) and represented a threefold induction of the basal VEGF level. Reverse transcriptase-polymerase chain reaction analysis of VEGF detected three mRNA species of 180, 312, and 384 bp corresponding, respectively, to VEGF121, VEGF165, and VEGF189. A 2.5- to 3.5-fold increase was observed for the 180- and 312-bp transcripts at 12 and 24 hours, respectively. FVII(a)-dependent VEGF production was inhibited by a pool of antibodies against TF, pointing to the involvement of this receptor. On specific active-site inhibition with dansyl-glutamyl-glycinyl-arginyl chloromethyl ketone, FVIIa lost 70% of its capacity to elicit VEGF production. Consistent with this, the native form (zymogen) of FVII only had a 1.8-fold stimulating effect. Protein tyrosine kinase and protein kinase C are involved in signal transduction leading to VEGF production, as shown by the inhibitory effects of genistein and GF 109203X. The results of this study indicate that TF is essential for VIIa-induced VEGF production by human fibroblasts and that its role is mainly linked to the proteolytic activity of the TF-VIIa complex.
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PMID:Tissue factor-dependent vascular endothelial growth factor production by human fibroblasts in response to activated factor VII. 953 78

The RNA genome of grapevine leafroll-associated closterovirus-3 (GLRaV-3) was cloned as a cDNA generated from GLRaV-3-specific dsRNA, and a partial genome sequence of 13154 nucleotides (nt) including the 3' terminus was determined. The sequenced portion contained 13 open reading frames (ORFs) potentially encoding, in the 5'-3' direction, proteins of > 77 kDa (ORF1a; helicase, HEL), 61 kDa (ORF1b; RNA-dependent RNA polymerase, RdRp), 6 kDa (ORF2), 5 kDa (ORF3, small transmembrane protein), 59 kDa (ORF4; heat shock protein 70, HSP70), 55 kDa (ORF5), 35 kDa (ORF6; coat protein, CP), 53 kDa (ORF7; diverged coat protein, CPd), 21 kDa (ORF8), 20 kDa (ORF9), 20 kDa (ORF10), 4 kDa (ORF11), 7 kDa (ORF12), and an untranslated region of 277 nt. ORF1b is probably expressed via a +1 ribosomal frameshift mechanism, most similar to that of lettuce infectious yellows virus (LIYV). Phylogenetic analysis using various gene sequences (HEL, RdRp, HSP70 and CP) clearly demonstrated that GLRaV-3, a mealybug-transmissible closterovirus, is positioned independently from aphid-transmissible monopartite closteroviruses (beet yellows, citrus tristeza and beet yellows stunt) and whitefly-transmissible bipartite closterovirus (lettuce infectious yellows, LIYV). However, another alleged mealybug-transmissible closterovirus, little cherry virus, was shown to be more closely related to the whitefly-transmissible LIYV than to GLRaV-3.
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PMID:Nucleotide sequence of the 3'-terminal two-thirds of the grapevine leafroll-associated virus-3 genome reveals a typical monopartite closterovirus. 960 46

The complete nucleotide sequence of a plasmid, pKJ50, isolated from an intestinal bacterium, Bifidobacterium longum KJ, has been determined. The plasmid was analysed and found to be 4960 bp in size with a G+C content of 61.7 mol%. Computer analysis of sequence data revealed three major ORFs encoding putative proteins of 31.5 (ORFI), 24.5 (ORFII) and 38.6 kDa (ORFIII). ORFI encodes a protein with a pI of 10.18 and shows relatively high amino acid sequence similarity (more than 60%) with several plasmid replication proteins from Gram-positive and -negative bacteria. Southern blot analysis showed that pKJ50 accumulates an ssDNA intermediate, suggesting that it replicates by a rolling-circle mechanism. Upstream of ORFI, three sets of repeated sequences resembling iteron structures of related plasmids were identified. ORFIII encodes a protein with a pI of 10.97. It also shows a high level of amino acid sequence similarity with some plasmid mobilization proteins. Upstream of ORFIII, a 12 bp stretch resembles an oriT DNA sequence with inverted repeats identical to those found in conjugative plasmids. Hydropathy plot analysis of ORFII, encoding an acidic protein (pI = 4.95), suggests it is a transmembrane protein. Several interesting palindromic sequences, repeat sequences and hairpin-loop structures around ORFI, which might confer regulatory effects on the replication of the plasmid, were also noted. Reverse transcriptase PCR (RT-PCR) and in vitro translation confirmed the expression of ORFI and ORFII. RT-PCR produced amplified DNA fragments of the expected sizes, corresponding to ORFI and ORFII. However, no RT-PCR product corresponding to ORFIII was obtained. In vitro translation showed protein bands of the expected sizes, corresponding to each ORF. A shuttle vector capable of transforming Bifidobacterium animalis MB209 was constructed by cloning pKJ50 and a chloramphenicol resistance gene into pBR322.
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PMID:Sequence analysis of plasmid pKJ50 from Bifidobacterium longum. 1021 92

Members of the tumor necrosis factor (TNF) family play important roles in modulation of immune responses. We describe the identification and cloning of a novel TNF family member that has been designated as TALL-1. TALL-1 is a 285-amino acid type II transmembrane protein. Its carboxy terminus shares approximately 35% sequence identity with the recently identified APRIL and approximately 20-25% with TNF, FasL, TRAIL, and lymphotoxin-alpha, suggesting that TALL-1 and APRIL belong to a subfamily of the TNF family of ligands. Northern blot analysis suggests that TALL-1 is expressed abundantly in peripheral blood leukocytes and weakly in spleen but is barely detectable in all other tissues examined. Reverse transcriptase-polymerase chain reaction analysis indicates that TALL-1 is specifically expressed in monocytes and macrophages but is undetectable in T and B lymphocytes. Furthermore, TALL-1 expression is dramatically down-regulated by phorbol myristate acetate/ionomycin.
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PMID:TALL-1 is a novel member of the TNF family that is down-regulated by mitogens. 1033 98

Osteoclasts or their precursors interact with the glycoprotein-enriched matrix of bone during extravasation from the vasculature, and upon attachment prior to resorption. Reverse transcriptase-PCR studies showed that two new alternatively spliced forms of chicken galectin-3, termed Gal-3TM1 and Gal-3TR1, were enriched and preferentially expressed in highly purified chicken osteoclast-like cells. Gal-3TM1 and Gal-3TR1 mRNA were also detected in chicken intestinal tissue, but not in kidney, liver, or lung. Gal-3TM1 and Gal-3TR1 messages both contain an open reading frame encoding a predicted 70-amino acid TM1 sequence inserted between the N-terminal Gly/Pro repeat domain and the carbohydrate recognition domain (exons 3 and 4). Gal-3TR1 mRNA contains an additional 241-bp sequence, which encodes a truncated open reading frame between the 4th and 5th exons, and, whose translation is expected to terminate within the carbohydrate recognition domain encompassing exons 4, 5, and 6. Immunoblotting and affinity chromatography showed that purified osteoclast preparations and intestinal homogenates contained a 36-kDa lactose-binding galectin. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analyses on chymotryptic peptides from the 36-kDa lectin confirmed its identity as Gal-3TM1. The TM1 insert contains a single transmembrane-spanning region and a leucine zipper-like stalk domain that is predicted to position the intact carbohydrate recognition domain of Gal-3TM1 on the exterior surface of the plasma membrane. Immunofluorescent staining of chicken osteoclasts confirmed the expression of Gal-3TM1 at the plasma membrane. Gal-3TM1 is the first example of a galectin superfamily member capable of being expressed as a soluble protein and as a transmembrane protein.
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PMID:New alternatively spliced form of galectin-3, a member of the beta-galactoside-binding animal lectin family, contains a predicted transmembrane-spanning domain and a leucine zipper motif. 1188 49

The endothelial cell protein C receptor (EPCR) is a type 1 transmembrane protein found primarily on endothelium that binds both protein C and activated protein C with similar affinity. EPCR augments the activation of protein C by the thrombin-thrombomodulin complex. To determine the physiological importance of EPCR, we generated EPCR-deficient mice by homologous targeting in embryonic stem cells. Genotyping of progeny obtained from EPCR(+/-) interbreeding indicated that EPCR(-/-) embryos died on or before embryonic day 10.5 (E10.5). Reverse transcriptase-PCR confirmed the absence of EPCR mRNA in EPCR(-/-) embryos. EPCR(-/-) embryos removed from extra-embryonic membranes and tissues at day E7.5 and cultured in vitro developed beyond E10.5, suggesting a role for EPCR in the normal function of the placenta and/or at the materno-embryonic interface. Immunohistochemistry revealed the lack of EPCR in trophoblast giant cells of EPCR(-/-) embryos. These cells, which normally express EPCR, are in direct contact with the maternal circulation and its clotting factors. In EPCR(-/-) embryos, greatly increased fibrin deposition was detected around these cells. To prevent this fibrin deposition, EPCR(+/-)-crossed female mice received a daily subcutaneous injection of enoxaparin through pregnancy. Although some EPCR(-/-) embryos were rescued from midgestational lethality, this regimen yielded no EPCR(-/-) pups. We conclude that EPCR is essential for normal embryonic development. Moreover, EPCR plays a key role in preventing thrombosis at the maternal-embryonic interface.
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PMID:Disruption of the endothelial cell protein C receptor gene in mice causes placental thrombosis and early embryonic lethality. 1221 60

The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) belongs to a class of membrane proteins termed tail-anchored proteins. Here, we show that the HCV RdRp C-terminal membrane insertion sequence traverses the phospholipid bilayer as a transmembrane segment. Moreover, the HCV RdRp was found to be retained in the endoplasmic reticulum (ER) or an ER-derived modified compartment both following transient transfection and in the context of a subgenomic replicon. An absolutely conserved GVG motif was not essential for membrane insertion but possibly provides a docking site for transmembrane protein-protein interactions. These findings have important implications for the functional architecture of the HCV replication complex.
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PMID:The hepatitis C virus RNA-dependent RNA polymerase membrane insertion sequence is a transmembrane segment. 1243 37

The halophilic bacterium Halomonas elongata accumulates K+, glutamate, and the compatible solute ectoine as osmoprotectants. By functional complementation of Escherichia coli mutants defective in K+ uptake, we cloned three genes that are required for K+ uptake in H. elongata. Two adjacent genes, named trkA (1,374 bp) and trkH (1,449 bp), were identified on an 8.5-kb DNA fragment, while a third gene, called trkI (1,479 bp), located at a different site in the H. elongata chromosome, was found on a second 8.5-kb fragment. The potential protein expressed by trkA is similar to the cytoplasmic NAD+/NADH binding protein TrkA from E. coli, which is required for the activity of the Trk K+ uptake system. The deduced amino acid sequences of trkH and trkI showed significant identity to the transmembrane protein of Trk transporters. K+ transport experiments with DeltatrkH and DeltatrkI mutants of H. elongata revealed that TrkI exhibits a Km value of 1.12 mM, while the TrkH system has a half-saturation constant of 3.36 mM. Strain KB12, relying on TrkH alone, accumulated K+ with a lower Vmax and required a higher K+ concentration for growth in highly saline medium than the wild type. Strain KB15, expressing only TrkI, showed the same phenotype and the same K+ transport kinetics as the wild type, proving that TrkI is the main K+ transport system in H. elongata. In the absence of both transporters TrkH and TrkI, K+ accumulation was not detectable. K+ transport was also abolished in a trkA deletion mutant, indicating that TrkI and TrkH depend on one type of TrkA protein. Reverse transcriptase PCR experiments and Northern hybridization analyses of the trkAH locus revealed cotranscription of trkAH as well as a monocistronic transcript with only trkA.
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PMID:Potassium transport in a halophilic member of the bacteria domain: identification and characterization of the K+ uptake systems TrkH and TrkI from Halomonas elongata DSM 2581T. 1565 81

Trophoblasts, a cell type found in the placenta, play a pivotal role in the function of the placenta as a barrier between the maternal fluid and the fetus. Recently, claudin, a 24-kDa transmembrane protein, was identified as being responsible for the barrier function of epithelia. In the present study, we investigated the expression profiles of claudin and the changes in expression during the differentiation of BeWo human trophoblast cells. Reverse transcriptase-polymerase chain reaction and immunoblotting demonstrated the expression of claudin-1, -3, -4, and -5 in BeWo cells. Forskolin, which induces the differentiation of BeWo cells from cytotrophoblast-like cells into syncytiotrophoblast-like cells, reduced slightly the expression of claudin-5. This is the first report to show changes in claudin-5 in forskolin-treated BeWo cells.
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PMID:Effect of forskolin on the expression of claudin-5 in human trophoblast BeWo cells. 1748 86


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