Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 447 male sterility trait in Vicia faba is strictly correlated with the presence of well-defined membranous vesicles or 'cytoplasmic spherical bodies' not found in fertile isogenic maintainer plants, and by the occurrence of a discrete high molecular weight double-stranded RNA. We have purified these cytoplasmic membranous vesicles and find that they contain the dsRNA together with an RNA-dependent RNA polymerase whose activity depends upon the presence of Mg2+, requires the four-nucleoside triphosphates and is unaffected by inhibitors of cellular transcriptases, e.g. alpha-amanitin and Actinomycin D. The dsRNA can be labelled in vitro by incubating the cytoplasmic vesicles with radioactive NTPs, and the RNA synthesized in vitro is also in a double-stranded form as judged by its resistance to RNase digestion at high salt and its behaviour upon CF-11 chromatography. Treatment of the vesicles with a non-ionic detergent releases the dsRNA in the form of a complex with the RNA-dependent RNA polymerase. The enzyme can still carry out the specific synthesis of dsRNA in these solubilized complexes. The cytoplasmic vesicles therefore isolate this vertically transmitted, self-replicating dsRNA from the cellular milieu: the possible mode of action and relevance of this novel genetic element to the 447 cytoplasmic male sterility trait are discussed.
 ...
PMID:The double-stranded RNA associated with the '447' cytoplasmic male sterility in Vicia faba is packaged together with its replicase in cytoplasmic membranous vesicles. 210 29

Ribonucleoprotein complexes isolated from measles virus-infected HeLa cells contained an RNA-dependent RNA polymerase activity that catalyzed the incorporation of ribonucleotides into ribonucleic acid. The ribonucleoprotein complexes were composed of measles virus nucleoprotein, phosphoprotein, and a large protein, as well as viral RNA. The kinetics of RNA synthesis at different temperatures, time intervals, and protein, ribonucleotide, and mono- and divalent cation concentrations were analyzed. Enzyme activity was maximum at 4 h at 25 degrees C in the presence of 100 mM Na+-2.5 mM Mg2+-1 mM ribonucleotides. Actinomycin D and alpha-amanitin had no effect on the enzyme activity. Addition of cytoplasmic extracts from uninfected HeLa cells to the reaction mixture did not increase the incorporation of ribonucleotides into RNA. The in vitro synthesized RNAs were characterize by slot blot analysis and quantitated by densitometer scanning. All mRNAs coding for the structural proteins of measles virus were synthesized. Nucleoprotein RNA was the most abundant species made, followed by phosphoprotein, hemagglutinin, fusion protein, matrix protein, and large-protein RNAs. The system described here resulted in the first efficient transcription of measles virus RNA and analysis of products.
 ...
PMID:Characterization of in vitro transcription and transcriptional products of measles virus. 366 51