The DEAD-Box p68/p72 Proteins and the Noncoding RNA Steroid Receptor Activator SRA: Eclectic Regulators of Disparate Biological Functions

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The DEAD-box family of RNA helicases has been highly conserved throughout evolution, and its members are found in all species, from bacteria to humans. While the ATP-dependent RNA helicase activity of the DEAD-box proteins was initially thought to be solely associated with a role in RNA metabolism, it is now becoming clear that some of the DEAD-box proteins such as p68 and p72, in addition to behaving as processive RNA helicases, are endowed with RNA ‘chaperone’ activity. It is through the latter property that these proteins regulate assembly and disassembly of RNA-protein complexes possibly by facilitating the formation of optimal RNA secondary structures through local RNA unwinding or other mechanisms1. Having such capabilitites, it is not surprising that the DEAD-box proteins take part in a wide variety of biological processes that involve RNA-protein interactions, such as transcription, ribosome biogenesis, pre-mRNA splicing and editing, RNA degradation, RNA export, ribosome assembly and translation. In this review we focus on recent studies that provide insights into the biological roles of p68 and p72, and their associated noncoding (nc) RNA Steroid Receptor RNA Activator (SRA), mainly addressing their involvement in transcriptional regulation and formation of protein complexes.