Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The autoantigen La, a known transcription termination factor of RNA polymerase III, was purified to homogeneity from mouse 3T3 cells and calf thymus by different isolation procedures. The La protein from calf thymus was separated into RNA binding and nonbinding subclasses. The murine La protein and the RNA binding subclass of calf thymus La protein showed ATPase/dATPase activity in the presence of DNA-RNA or RNA-RNA hybrids. A novel monoclonal anti-La antibody (La11G7) and patients' anti-La antibodies immunoadsorbed to homogeneously purified La protein were able to inhibit the enzyme activity of La protein. La protein was able to melt a synthetic DNA-RNA hybrid in a reaction that required ATP hydrolysis. The RNA binding ability of the nonbinding subclass was restored by treatment with sialidase. This treatment also restored the protein's ATP-dependent melting activity.
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PMID:Characterization of the autoantigen La as a nucleic acid-dependent ATPase/dATPase with melting properties. 168 13

Infective trypomastigote forms of Trypanosoma cruzi express an oligomeric trans-sialidase that contains a long stretch of 12-amino-acid repeats at the C terminus, while the insect epimastigote forms having a monomeric trans-sialidase without repeats. Here we show that messenger RNAs encoding trans-sialidases containing the repeats are not present in epimastigotes but are abundant in trypomastigotes. In contrast, mRNA species encoding the conserved N-terminal domain are detected in epimastigotes. A cDNA clone derived from epimastigote mRNA was isolated and characterized. It predicts a repeat-minus amino-acid sequence that has 84% identity to the conserved N-terminal domain of trypomastigote trans-sialidase, and contains some of the necessary amino acids for the catalytic activity, as shown by fusion experiments. Transcripts corresponding to this clone were detected in epimastigotes and in trypomastigotes by reverse-transcriptase and polymerase chain reaction. In addition, the lack of repeats is not due to RNA processing because the corresponding gene without repeats was amplified from the parasite DNA. These results suggest that a distinct set of genes encode the repeat-minus trans-sialidase, and only these trans-sialidase genes are expressed in epimastigote forms.
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PMID:Trypanosoma cruzi trans-sialidase gene lacking C-terminal repeats and expressed in epimastigote forms. 763 18

The cell density-dependent growth inhibition of human SK-N-MC neuroblastoma cells is initiated by increased ganglioside sialidase activity leading to elevated cell surface presentation of ganglioside GM1, a ligand of galectin-1. We herein show that the extent of the cell surface expression of the galectin coincides with marked increases of the sialidase activity. Reverse transcriptase-polymerase chain reaction analysis excludes a regulation at the transcriptional level. Exposure of cells to purified galectin-1 reveals its carbohydrate-dependent activity to reduce cell proliferation. Assays to detect DNA fragmentation biochemically and cytometrically and to block caspases render it unlikely that galectin-1 acts as a classical proapoptotic factor on these cells. Because the chimeric galectin-3 shares binding sites and binding parameters with galectin-1 for these cells, we tested whether this galectin will elicit the same response as the homodimeric cross-linking galectin-1. Evidently, galectin-3 fails to affect cell growth by itself but interferes with galectin-1 upon coincubation. Its proteolytically truncated variant, the C-terminal lectin domain with impaired capacity to form aggregates when surface bound, has only weak binding properties. Thus, the way in which the galectin-1 interacts topologically with an apparently common set of ligands relative to galectin-3 is crucial for eliciting post-binding events. We conclude that galectin-1 is a probable effector in the sialidase-dependent growth control in this system. Moreover, the experiments with galectin-3 reveal functional divergence, most probably based on different topologies of presentation of homologous carbohydrate-binding sites.
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PMID:Negative regulation of neuroblastoma cell growth by carbohydrate-dependent surface binding of galectin-1 and functional divergence from galectin-3. 1145 61