Adaptor Aly and co-adaptor Thoc5 function in the Tap-p15-mediated nuclear export of HSP70 mRNA

• Published in: The EMBO journal Vol. 28; no. 5; pp. 556 - 567
• Main Authors: Katahira, Jun, Inoue, Hitomi, Hurt, Ed, Yoneda, Yoshihiro
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 04.03.2009; Nature Publishing Group UK; Blackwell Publishing Ltd; Nature Publishing Group
• Subjects: Active Transport, Cell Nucleus; Amino Acid Sequence; Binding sites; Cell Line; Cell Nucleus - metabolism; EMBO36; heat shock mRNA; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Humans; Mammals; Models, Molecular; Molecular biology; Molecular Sequence Data; Nuclear Proteins - metabolism; nucleo-cytoplasmic transport; Nucleocytoplasmic Transport Proteins - physiology; Proteins; Ribonucleic acid; RNA; RNA, Messenger - metabolism; RNA-Binding Proteins - metabolism; RNA-Binding Proteins - physiology; Transcription Factors - metabolism; TREX complex; nucleo‐cytoplasmic transport; heat shock mRNA; TREX complex
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/emboj.2009.5

In metazoans, nuclear export of bulk mRNA is mediated by Tap‐p15, a conserved heterodimeric export receptor that cooperates with adaptor RNA‐binding proteins. In this article, we show that Thoc5, a subunit of the mammalian TREX complex, binds to a distinct surface on the middle (Ntf2‐like) domain of Tap. Notably, adaptor protein Aly and Thoc5 can simultaneously bind to non‐overlapping binding sites on Tap‐p15. In vivo , Thoc5 was not required for bulk mRNA export. However, nuclear export of HSP70 mRNA depends on both Thoc5 and Aly. Consistent with a function as a specific export adaptor, Thoc5 exhibits in vitro RNA‐binding activity and is associated with HSP70 mRNPs in vivo as a component of the stable THO complex. Thus, through the combinatorial use of an adaptor (e.g., Aly) and co‐adapter (e.g., Thoc5), Tap‐p15 could function as an export receptor for different classes of mRNAs.