Human mRNA export machinery recruited to the 5' end of mRNA.
Pre-mRNAs undergo splicing to remove introns, and the spliced mRNA is exported to the cytoplasm for translation. Here we investigated the mechanism for recruitment of the conserved mRNA export machinery (TREX complex) to mRNA. We show that the human TREX complex is recruited to a region near the 5' end of mRNA, with the TREX component Aly bound closest to the 5' cap. Both TREX recruitment and mRNA export require the cap, and these roles for the cap are splicing dependent. CBP80, which is bound to the cap, associates efficiently with TREX, and Aly mediates this interaction. Together, these data indicate that the CBP80-Aly interaction results in recruitment of TREX to the 5' end of mRNA, where it functions in mRNA export. As a consequence, the mRNA would be exported in a 5' to 3' direction through the nuclear pore, as observed in early electron micrographs of giant Balbiani ring mRNPs.
Cheng
Hong
H
Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Dufu
Kobina
K
Lee
Chung-Sheng
CS
Hsu
Jeanne L
JL
Dias
Anusha
A
Reed
Robin
R
D005091:Exons; D006801:Humans; D008957:Models, Genetic; D039502:Nuclear Cap-Binding Protein Complex / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D012326:RNA Splicing; D034443:RNA Transport; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
C105242:ALYREF protein, human; D039502:Nuclear Cap-Binding Protein Complex; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors