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)

A monoclonal antibody raised to a Teladorsagia circumcincta 31-33 kDa doublet antigen was used to immunoscreen a T. circumcincta cDNA expression library. Sheep antibodies eluted from the proteins expressed by two clones immunopositive with the monoclonal antibody specifically recognised the doublet antigen on Western blots of third stage larval extract, confirming that these clones coded for the antigen. Database searches revealed high levels of similarity with beta-galactoside-binding lectin-like proteins (Ga1BPs or galectins) from Caenorhabditis elegans and Onchocerca volvulus. By analogy with these sequences, both T. circumcincta cDNA clones contain the full-length protein coding region. The native doublet proteins could be preferentially extracted from homogenates of third stage larvae with lactose and could be affinity purified on an asialofetuin column, confirming the identity of these bands as galectins. Reverse transcriptase-polymerase chain reaction amplification using a primer based on the C. elegans Spliced Leader SL1 sequence showed that the corresponding T. circumcincta mRNAs are also trans-spliced at their 5' ends. While there are considerable nucleotide differences between the two clones, the majority are located in the non-coding regions. Within the coding region there are 87 nucleotide differences but only three of these result in amino acid substitutions.
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PMID:cDNA cloning of galectins from third stage larvae of the parasitic nematode Teladorsagia circumcincta. 920 Jan 21

Hepatitis E virus (HEV) is the major cause of acute epidemic and sporadic hepatitis in the developing world. It is a positive-strand RNA virus with a genome length of about 7.2 kb. The replication mechanism of this virus is virtually unexplored. Identification of the regulatory elements involved in initiation of replication may help in designing specific inhibitors for therapy. In the positive-stranded RNA viruses the initiation of replication requires interaction of the 3' end of genome with its RNA-dependent RNA polymerase (RdRp) and possibly host-derived cofactors for synthesis of the minus-strand replicative intermediate. Secondary structure prediction of the conserved 3' end of the infectious HEV genome was carried out to identify possible stem-loop structures necessary for RNA-protein interaction and the model was confirmed by structure probing experiments. Electrophoretic mobility-shift assays showed specific binding of purified and refolded recombinant HEV RdRp protein to the 3' end of its RNA genome containing the poly(A) stretch. Mutations at the 3' end, in which the stem-loop structures were partially or completely destroyed or recreated revealed that the two stem-loop structures SL1 and SL2 at the 3' end and the poly(A) stretch are necessary for this binding. The interacting nucleotides in such an interaction were further identified by generating footprints of the complex by Pb(II)-induced hydrolysis. This specific binding of viral RdRp to the 3' end of HEV RNA directs the synthesis of complementary-strand RNA and thus such a binding domain might assume the role of a possible cis-acting element as a potential site for the initiation of replication.
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PMID:The 3' end of hepatitis E virus (HEV) genome binds specifically to the viral RNA-dependent RNA polymerase (RdRp). 1125 93

An important characteristic of the transcription of a ribosomal RNA gene (rDNA) mediated by DNA-dependent RNA polymerase (Pol) I is its stringent species specificity. SL1/TIF-IB is a key complex for species specificity, but its functional complex has not been reconstituted. Here, we established a novel and highly sensitive monitoring system for Pol I transcription to reconstitute the SL1 activity in which a transcript harboring a reporter gene synthesized by Pol I is amplified and converted into translatable mRNA by the influenza virus RNA-dependent RNA polymerase. Using this monitoring system, we reconstituted Pol I transcription from the human rDNA promoter in mouse cells by expressing four human TATA-binding protein (TBP)-associated factors (TAFIs) in the SL1 complex. The reconstituted SL1 also re-activated human rDNA transcription in mouse A9 cells carrying an inactive human chromosome 21 that contains the rDNA cluster. Chimeric SL1 complexes containing human and mouse TAFIs could be formed, but these complexes were inactive for human rDNA transcription. We conclude that four human TAFIs are necessary and sufficient to overcome the barrier of species specificity for human rDNA transcription in mouse cells.
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PMID:Reconstitution of human rRNA gene transcription in mouse cells by a complete SL1 complex. 2492 1