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. Author manuscript; available in PMC: 2008 Oct 9.
Published in final edited form as: Virology. 2007 Feb 27;363(2):376–386. doi: 10.1016/j.virol.2007.01.026

Figure 7. Overview of cellular mRNA and unspliced retroviral RNA export.

Figure 7

Cellular mRNA export is mediated by the addition of REF/Aly during mRNA splicing, which recruits Tap and p15 to promote nuclear export. The RNA helicase Dbp5 is also involved in this export pathway. HIV employs the RRE, which binds the viral Rev protein, which in turn binds Crm1. This export pathway is Tap-independent, and instead uses DDX3 as the RNA helicase associated with export. MPMV utilizes the CTE to export unspliced viral RNAs. This structured element binds Tap directly and accesses the cellular mRNA pathway, presumably including p15 (Jin et al., 2003) and the helicase Dbp5. RSV uses the DR elements to recruit a yet unidentified adapter protein “X,” which in turn binds Tap and presumably p15. This complex is then targeted for nuclear export via Dbp5.