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Updated: Jul 31, 2026
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Measuring the Kinetics of mRNA Transcription in Single Living Cells
Published on: August 25, 2011
Una imagen de congelación de la transcripción eucariota durante el alargamiento y el encapsulamiento del ARNm
Science (New York, N.Y.)
|February 21, 1992
Resumen
La identidad del ARN mensajero (ARNm) se establece durante la transcripción. La polimerasa de ARN de Vaccinia se une a un segmento de ARN de 18 nucleótidos, y se produce el encapsulamiento 5' en cadenas nacientes más largas, lo que sugiere un mecanismo de cotranscripción.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Virología Virología.
Sus antecedentes:
- El ARN mensajero (ARNm) sufre modificaciones cruciales para su función.
- El momento preciso y los mecanismos de estas modificaciones durante la transcripción son clave para la expresión génica.
Objetivo del estudio:
- Para investigar el sitio de unión al ARN de la vacuna ARN polimerasa.
- Determinar el momento y los requisitos para el tope de 5' del ARNm naciente.
- Para aclarar el mecanismo de establecimiento de la identidad del ARNm cotranscripcional en eucariotas.
Principales métodos:
- Huella de la ribonucleasa para mapear las interacciones ARN-proteína.
- Análisis de los complejos ternarios de la vacuna ARN polimerasa.
- Pruebas bioquímicas con enzimas de capping purificadas.
Principales resultados:
- Se identificó un sitio de unión de ARN de 18 nucleótidos en la vacuna ARN polimerasa.
- Las dimensiones del sitio de unión se mantuvieron constantes durante la translocación de la polimerasa.
- El encapsulamiento 5' fue cotranscripcional, ocurriendo en cadenas de ARN nacientes ≥31 nucleótidos.
- La enzima de captura forma un complejo binario con la ARN polimerasa independientemente de los ácidos nucleicos.
Conclusiones:
- La ARN polimerasa de Vaccinia posee un sitio definido de unión al ARN crucial para la transcripción.
- El encapsulamiento 5' está integrado en el proceso de transcripción, que ocurre en el ARN naciente suficientemente largo.
- Estos hallazgos proponen un modelo de cómo se establece la identidad del ARNm durante la transcripción en eucariotas.
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Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a “cap” to the 5’ end of the growing transcript. In this process, a 5’ phosphate is replaced by modified guanosine that has a methyl group attached to it (7-Methyl guanosine). This 5’ cap helps the...
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Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
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02:01Pre-mRNA Processing
In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or pre-mRNA to distinguish it from mature mRNA.
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a “cap” to the 5’ end of the growing transcript. In this process, a 5’ phosphate is replaced by modified guanosine that has a methyl group attached to it (7-Methyl guanosine). This 5’ cap helps the...
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a “cap” to the 5’ end of the growing transcript. In this process, a 5’ phosphate is replaced by modified guanosine that has a methyl group attached to it (7-Methyl guanosine). This 5’ cap helps the...
01:53Bacterial Transcription
RNA polymerase (RNAP) carries out DNA-dependent RNA synthesis in both bacteria and eukaryotes. Bacteria do not have a membrane-bound nucleus. So, transcription and translation occur simultaneously, on the same DNA template.
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
02:35Transcription Elongation Factors
Transcription elongation is a dynamic process that alters depending upon the sequence heterogeneity of the DNA being transcribed. Hence, it is not surprising that the elongation complex's composition also varies along the way while transcribing a gene.
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
The transcription elongation is regulated via pausing of RNA polymerase on several occasions during transcription. In bacteria, these halts are necessary because the transcription of DNA into mRNA is coupled to the translation of that mRNA into a...
01:35Pre-mRNA Processing: Modification of pre-mRNA Ends
In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or pre-mRNA to distinguish it from mature mRNA.
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...
Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a cap to the 5' end of the growing transcript. In this process, a 5' phosphate is replaced by modified guanosine that has a methyl group attached (7-methyl guanosine). This 5' cap helps the cell...