Eukaryotic transcription (original) (raw)
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Eukaryotic transcription is the elaborate process that eukaryotic cells use to copy genetic information stored in DNA into units of RNA replica. A eukaryotic cell has a nucleus that separates the processes of transcription and translation. Eukaryotic transcription occurs within the nucleus where DNA is packaged into nucleosomes and higher order chromatin structures.
The Transcription Unit of Ribosomal Genes Is Attached to the Nuclear Skeleton
Experimental Cell Research, 1996
proposed that active polymerases form part of the The relationship between various loci of the ribo-nucleoskeleton while the genes pass through such fixed somal gene repeat and the nucleoskeleton was exam-polymerizing sites [for review, see 22]. Thus, there is ined in agarose-embedded HeLa cells. The accessibilconvincing evidence that the nucleoskeleton is more ity of intranucleolar structures to molecular probes than a passive network with only structural functions.
Organization, Transcription, Transcriptome and Post- transcriptional Modifications of Eukaryotic DNA
Eukaryotic DNA is associated with tightly bound basic proteins, called histones. These serve to order the DNA into fundamental structural units, called nucleosomes, that resemble beads on a string. Nucleosomes are further arranged into increasingly more complex structures that organize and condense the long DNA molecules into chromosomes that can be segregated during cell division. Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNAby the enzyme RNA polymerase. The process of eukaryotic transcription is separated into three phases, initiation, elongation, and termination. It is a complex process involving various cell signaling techniques as well as the action of many enzymes. The following information is a detailed description of eukaryotic transcription. The transcription of eukaryotic genes is regulated by interactions between proteins and DNA sequences within or near the genes. Transcription is initiated in the promoter of a gene, the region recognized by the RNA polymerase. However, the accurate initiation of transcription from eukaryotic gene promoters requires several accessory proteins, or basal transcription factors. Transcriptome can be defined as the complete set of RNA transcripts produced by the genome at a given time. Transcriptome is highly dynamic and complex in comparison to the relatively stable genome. Post transcriptional modification is a process in cell biology by which, in eukaryotic cells, primary transcript RNA is converted into mature RNA. A notable example is the conversion of precursor messenger RNA into mature messenger RNA, which occurs prior to protein synthesis.
Nucleic Acids Research, 2003
By employing puri®ed transcription factors and RNA polymerase III (pol III), we generated active pol III transcription complexes on the human 5S rRNA gene. These large complexes were separated by size exclusion chromatography from nonincorporated proteins. In addition, we succeeded in isolating speci®c intermediate stages of complex formation. Such isolated partial complexes require complementation with the missing activities for full transcription activity. One central ®nding is that a 5S DNA±TFIIIA±TFIIIC2±TFIIIBb complex could be isolated which had been assembled in the absence of the general pol III transcription factor IIIC1. Thus TFIIIC1 is not an assembly factor for other transcription factors. Although pol III has the potential to bind unspeci®cally to DNA, such polymerase molecules cannot be rendered initiation competent by direct recruitment to a 5S DNA±TFIIIA±TFIIIC2± TFIIIBb complex, but this process strictly requires additional TFIIIC1 activity. This clearly demonstrates that in contrast to yeast cells, hTFIIIB(b), although required, does not suf®ce for the functional recruitment of polymerase III. These data document that TFIIIC1 is the second transcription factor required for the recruitment of pol III in mammalian cells.
Genes & Development, 1994
Previously, we have isolated mutants of Saccharomyces cerevisiae primarily defective in the transcription of 35S rRNA genes by RNA polymerase I and have identified a number of genes (RRN genes) involved in this process. We have now cloned the RRN6 and RRN7 genes, determined their nucleotide sequences, and found that they encode proteins of calculated molecular weights of 102,000 and 60,300, respectively. Extracts prepared from rrn6 and rrn7 mutants were defective in in vitro transcription of rDNA templates. We used extracts from strains containing epitope-tagged wild-type Rrn6 or Rrn7 proteins to purify protein components that could complement these mutant extracts. By use of immunoaffinity purification combined with biochemical fractionation, we obtained a highly purified preparation (Rrn6/7 complex), which consisted of Rrn6p, Rrn7p, and another protein with an apparent molecular weight of 66,000, but which did not contain the TATA-binding protein (TBP). This complex complemented both rrn6 and rrn7 mutant extracts. Template commitment experiments carried out with this purified Rm6/7 complex and with rrn6 mutant extracts have demonstrated that the Rrn6/7 complex does not bind stably to the rDNA template by itself, but its binding is dependent on the initial binding of some other factor(s) and that the Rrn6/7 complex is required for the formation of a transcription-competent preinitiation complex. These observations are discussed in comparison to in vitro rDNA transcription systems from higher eukaryotes.
Molecular and Cellular Biology, 1986
We have studied the protein components and nucleic acid sequences involved in stably activating the ribosomal DNA (rDNA) template and in directing accurate transcription of mammalian rRNA genes. Two protein components are necessary to catalyze rDNA transcription, and these have been extensively purified. The first, factor D, can stably associate by itself with the rDNA promoter region and is responsible for template commitment. The second component, factor C, which appears to be an activated subset of polymerase I, can stably bind to the factor D-rDNA complex but not to the rDNA in the absence of factor D. A third component which had been previously identified as a rDNA transcription factor is shown to be a RNase inhibitor. Extending our earlier observation that the approximately 150-base-pair mouse rDNA promoter consists of a minimal essential region (residues approximately -35 to approximately +9) and additional upstream stimulatory domains, we now report that each of these promot...