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)

Examination of cDNAs for the laminin-binding alpha 7 integrin subunit identified two different sequences (designated X1 and X2) coding for the variable region between the III and IV homology repeat domains near the putative ligand-binding site. Sequencing of a mouse alpha 7 genomic clone established that the X1 and X2 regions are derived by mutually exclusive alternative mRNA splicing. Reverse transcriptase-polymerase chain reaction analysis of alpha 7 mRNA indicated that the X1 and X2 isoforms were present in equal amounts in mouse skeletal myoblasts and adult heart. However, in adult skeletal muscle, the X2 variant was exclusively expressed. Amino acid sequence homologies in the III/IV segment suggest that alpha 3 and alpha 6 are also alternatively spliced at this site. We identified alternatively spliced exons in a human alpha 6 genomic clone that encode X1- and X2-like segments. Analysis of the alpha 7 cytoplasmic domain indicated that this region was also alternatively spliced and like alpha 3 and alpha 6 could exist as the A or B form. In mouse skeletal and cardiac muscle the B form of alpha 7 was strongly expressed. However, we identified alpha 7A in neonate and adult skeletal muscle but not in cardiac tissue. High levels of alpha 7A were detected in differentiating myotubes, but in proliferating myoblasts only the alpha 7B isoform was present. These results indicate that alternative splicing of alpha 7 mRNA is differentially regulated during development and generates variant integrin chains with structurally and presumably functionally unique ligand-binding and cytoplasmic domains.
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PMID:Alternative extracellular and cytoplasmic domains of the integrin alpha 7 subunit are differentially expressed during development. 825 14

We report the cloning of two full-length cDNAs coding for the human beta 1-integrin which diverge from each other for their 5'-untranslated sequences. Characterization of a genomic clone containing these two sequences showed that they are contiguous, spaced by 261 nucleotides, and both followed by donor splice sites. Analysis by primer extension and transient transfection in a human osteogenic sarcoma cell line (MG-63) demonstrated the existence of two independent promoters for transcription initiation. The two promoter regions are very G+C-rich, and lack both a TATA box and a CAAT box. Northern blot analysis showed that transcripts starting from the distal promoter (with respect to the first coding exon) are at least 20-fold more abundant than transcripts originating from the proximal one. The levels of both transcripts increase after transforming growth factor-beta 1 induction, however, mRNAs originating from the proximal promoter increase at an higher extent. Reverse transcriptase/polymerase chain reaction analysis performed on different human tissues and cell lines revealed that, while the distal promoter is ubiquitously active, the proximal promoter is not. These findings suggest a possible complex pattern for regulation of the human beta 1-integrin gene expression.
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PMID:Human beta 1-integrin gene expression is regulated by two promoter regions. 844 90

A VH gene segment that could not be assigned to any of the six known VH gene families of the channel catfish was identified in a genomic clone containing VH gene segments. This gene segment (designated VH7.1) exhibited the structural features characteristic of vertebrate VH genes, specifically potential upstream regulatory sequences, a leader sequence split by an intron, a reading frame that could be readily divided into framework and complementarity determining regions, and a 3' recombination signal sequence. Two regions of nucleotide deletions coupled with degeneracy in the nonamer sequence indicate that this VH gene segment is a pseudogene. Genomic DNA restricted with different enzymes and hybridized under stringent conditions with probes derived from VH7.1 showed that 8-10 bands were present in Southern blots. Reverse transcriptase PCR approaches were used to determine if any of these related sequences were expressed. Sequence analysis of cloned PCR products indicates that different VH gene segments exhibiting > 80% similarity to germline VH7.1 are expressed. Multiple sequence alignments showed that the expressed cVH7a cDNA sequence shared less than 60% nucleotide similarity with representative cDNA sequences from the other known catfish VH gene families. These combined results thus fulfil the criteria for the definition of a new family of catfish VH gene segments. This newly defined, small VH family is designated VH7.
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PMID:Characterization of a seventh family of immunoglobulin heavy chain VH gene segments in the channel catfish, Ictalurus punctatus. 883 18

To understand the regulation, evolution, and genetics of lp(A2)/Edg4, a second lysophosphatidic acid receptor gene, we characterized its complete cDNA sequence, genomic structure, and chromosomal location. The full-length mouse transcript sequence was determined using rapid amplification of cDNA ends. Southern blot and restriction fragment length polymorphism segregation analyses revealed that the mouse gene was present as a single copy and located at the middle of Chromosome 8 near the mutations for myodystrophy (myd) and "kidney-anemia-testes" (kat). This region is syntenic with human chromosome 19p12, where the human genomic clone containing the lp(A2) gene (EDG4) was mapped. Sequence analysis of genomic clones demonstrated that both mouse and human transcripts were encoded by three exons, with an intron separating the coding region for transmembrane domain VI. Reverse transcriptase-PCR demonstrated that the three exons were spliced in all mouse tissues shown to express the transcript. Finally, in a comparison of all human lp(A2) sequences present in the database, we identified several sequence variants in multiple tumors. One such variant (a G deletion) in the initially characterized Edg4 cDNA clone (derived from an ovarian tumor) results in a frameshift mutation near the 3' end of the coding region. In addition to increasing our understanding of the mechanisms underlying lysophosphatidic acid signaling and lysophospholipid receptor gene evolution, these results have important implications regarding the genomic targeting and oncogenic potential of lp(A2).
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PMID:Genomic characterization of the lysophosphatidic acid receptor gene, lp(A2)/Edg4, and identification of a frameshift mutation in a previously characterized cDNA. 1072 22

A genomic clone and the corresponding cDNA of a new Arabidopsis monosaccharide transporter AtSTP9 were isolated. Transport analysis of the expressed protein in yeast showed that AtSTP9 is an energy-dependent, uncoupler-sensitive, high-affinity monosaccharide transporter with a K(m) for glucose in the micromolar range. In contrast to all previously characterized monosaccharide transporters, AtSTP9 shows an unusual specificity for glucose. Reverse transcriptase-polymerase chain reaction analyses revealed that AtSTP9 is exclusively expressed in flowers, and a more detailed approach using AtSTP9 promoter/reporter plants clearly showed that AtSTP9 expression is restricted to the male gametophyte. AtSTP9 expression is not found in other floral organs or vegetative tissues. Further localization on the cellular level using a specific antibody revealed that in contrast to the early accumulation of AtSTP9 transcripts in young pollen, the AtSTP9 protein is only found weakly in mature pollen but is most prominent in germinating pollen tubes. This preloading of pollen with mRNAs has been described for genes that are essential for pollen germination and/or pollen tube growth. The pollen-specific expression found for AtSTP9 is also observed for other sugar transporters and indicates that pollen development and germination require a highly regulated supply of sugars.
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PMID:Functional characterization and expression analyses of the glucose-specific AtSTP9 monosaccharide transporter in pollen of Arabidopsis. 1297 Apr 85

Researches on genes expressed in a cercarial stage-specific manner may help us understand the molecular events and functions during schistosome invasion of skin. A genomic clone encoding 8-kDa calcium-binding protein (SjCa8) specifically expressed in cercariae and skin-stage schistosomulum (transformed within 3 h) was obtained from cercariae. Recombinant protein was expressed in vector pET32a (+) and purified using a Ni-NTA purification system. The target protein SjCa8 was determined by matrix-assisted laser desorption/ionization time-of-flight (TOF)/TOF mass spectrometer after thrombin digestion and dialysis. Reverse transcriptase polymerase chain reaction and Western blot revealed SjCa8 can be detected in cercaria and skin-stage schistosomulum but not lung-stage schistosomulum, adult, or egg and was localized to head gland, penetration gland tubes, and penetration glands where Ca(2+) was abundant, and the cercarial tegument (but not tegument of tail) and body-tail junction. Furthermore, SjCa8 was interestingly detected in cercarial secretions. The characterization of SjCa8 indicated that it may undergo structural and physiological modifications, including repair of the surface membrane, changes in permeability that account for the loss of water tolerance, activities of calcium-depending enzymes, and immune signaling, etc. Furthermore, vaccination with rSjCa8 plus adjuvant induced protective effect with 50.39% worm reduction rate and significantly high hepatic and intestine egg reduction rates (54.16%, 50.63%, respectively), which is possibly mediated through an apparent induction of Th1-type immune response for strikingly high level of IgG2a and IgG2b developed in immunized C57BL/6 mice.
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PMID:Expression profile, localization of an 8-kDa calcium-binding protein from Schistosoma japonicum (SjCa8), and vaccine potential of recombinant SjCa8 (rSjCa8) against infections in mice. 1901 78

A cotton (Gossypium hirsutum L.) genomic clone encompassing a 17.9-kb DNA fragment was found to contain a delta-12 fatty acid desaturase gene (designated FAD2-4). The FAD2-4 open reading frame has 1,155bp and is uninterrupted, encoding a conceptual FAD2-4 polypeptide of 384 amino acids that has 98% identity with the cotton FAD2-3 polypeptide. The FAD2-4 gene has a single intron of 2,780 bp in its 5'-untranslated region (5'-UTR). The 3'-flanking regions and 5'-UTR introns in the FAD2-4 and FAD2-3 genes are quite different, indicating that the genes might be paralogs in the cotton genome. Reverse transcriptase (RT)-PCR analysis indicated that the FAD2-4 and FAD2-3 genes were expressed in all tissues examined, including seeds, seedling tissues, young and mature leaves, roots, stems, developing flower buds, and ovule fibers. These constitutive patterns of expression were notably different from that of the FAD2-1 gene, which was restricted to seeds and developing flower buds, or to the expression of a newly-identified FAD2-2 gene isoform, which was barely detectable in roots, hypocotyls, stems, and fibers, but was expressed in all other tissues. The FAD2-4 coding region was expressed in yeast and shown to encode a functional delta-12 desaturase, converting oleic acid (C18:1) to linoleic acid (C18:2) in recombinant yeast cells. In addition, both the FAD2-4 and the FAD2-3 genes were transferred into the Arabidopsis thaliana fad2-1 mutant background where they effectively restored wild type fatty acid composition and growth characteristics. Finally, the cotton FAD2-4 green fluorescent protein (GFP) fusion polypeptide appeared to be localized in the endomembrane system of transgenic Arabidopsis plants in the complemented fad2-1 mutant background, supporting a functional ER location for the cotton FAD2-4 polypeptide in this heterologous plant system. Thus, a new functional member of the FAD2 gene family in cotton has been characterized, indicating a complex regulation of membrane lipid desaturation in this important fiber/oilseed crop.
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PMID:Identification and expression of a new delta-12 fatty acid desaturase (FAD2-4) gene in upland cotton and its functional expression in yeast and Arabidopsis thaliana plants. 1921 93