Active RNase I is not present inside cells, and accordingly, most RNase I is present in the periplasm of gram-negative cells. However, a small pool of RNase I is present intracellularly, although presumably in an inactive state. How it is kept inactive is unclear; presumably, the reducing environment of the cell plays a role, and the possibility of an RNase I inhibitor, analogous to the RNase inhibitor in eukaryotic cells, also needs to be considered.
A large number of agents or conditions promote the breakdown of cellular RNA, which consists primarily of rRNA. In many cases, these agents or conditions affect the cell membrane, which could allow the entry of periplasmic RNase I into the cytoplasm resulting in the extensive RNA turnover observed. (PMID: 19215777)
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Last modification of this entry: July 11, 2012.