Repeat untranscribed DNA sequences are generally thought to be genetic junk at best, harmful at worst, but in ribosomes they are essential to repairing DNA damage, according to a study published this week in Science.
Ribosomal DNA (rDNA) codes for the RNA that makes up a major component of ribosomes, the site of protein synthesis. Ribosomal RNA (rRNA) comprises 80% of the RNA found in a typical cell and is highly conserved from bacteria to humans. Virtually every species has a different number of these untranscribed repeats in their rDNA - from only a few in bacteria to thousands in plants and animals. Why these repeat copies were present in the cell was not known, but now researchers at the National Institute of Genetics (NIG) in Mishima, Japan, have shown that these repeat arrays are critical in two processes that facilitate DNA repair....
Ribosomal protein complex
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