Nuclear RNA polymerases IV and V
Pikaard, Craig S. Department of Biology, Washington University, St. Louis, Missouri.
- Pol IV, Pol V, and transcriptional gene silencing
- Pol IV and Pol V in flowering and stress responses
- Pol IV and mobile silencing signals
- Origins of Pol IV and Pol V
- Priorities for future studies
- Links to Primary Literature
- Additional Readings
In all living cells, genetic information stored as deoxyribonucleic acid (DNA) is copied into ribonucleic acid (RNA) polymers that mediate the chemical transactions of life. For instance, messenger RNAs (mRNAs) carry the codes for proteins to the ribosomes, where proteins are made. So-called noncoding RNAs (ncRNAs) that do not encode proteins also carry out essential functions. For instance, ribosomal RNAs (rRNAs) and transfer RNAs (tRNAs) are essential for protein synthesis. Other ncRNAs guide RNA processing events. Because of the importance of RNA, the enzymes that transcribe DNA into RNA, known as DNA-dependent RNA polymerases, are critical to life. Bacteria and archaea have a single DNA-dependent RNA polymerase. However, in eukaryotic organisms, including fungi, plants, and animals, three different DNA-dependent RNA polymerases, abbreviated as Pol I, Pol II, and Pol III, are essential for cell viability (see table). It was long assumed that eukaryotes use only Pol I, II, and III. However, the sequencing of the Arabidopsis thaliana genome revealed that plants possess two additional nuclear RNA polymerases, Pol IV and Pol V (formerly known as Pol IVa and Pol IVb, respectively) that are not strictly required for cell survival but that specialize in the production of ncRNAs that mediate gene silencing.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information