Spliceosome RNA helicase DDX39B (DDX39B)

Involved in nuclear export of spliced and unspliced mRNA. Assembling component of the TREX complex that's believed to couple mRNA transcription, processing and nuclear export, and specifically associates with spliced mRNA and not with unspliced pre-mRNA.

TREX is recruited to spliced mRNAs with a transcription- independent mechanism, binds to mRNA upstream of the exon-junction complex (EJC) and can be recruited in a splicing- and cap-dependent manner to a region near the 5' end of the mRNA where it functions in mRNA export to the cytoplasm via the TAP/NFX1 pathway. May undergo several rounds of ATP hydrolysis during assembly of TREX to induce subsequent loading of elements like ALYREF/THOC and CHTOP on mRNA.