DDX39B
Description
The DDX39B (DExD-box helicase 39B) is a protein-coding gene located on chromosome 6.
DDX39B is involved in the nuclear export of both spliced and unspliced mRNA. It is a key component of the TREX complex, which couples mRNA transcription, processing, and nuclear export. DDX39B specifically associates with spliced mRNA, not with unspliced pre-mRNA. TREX is recruited to spliced mRNAs through a transcription-independent mechanism, binding to mRNA upstream of the exon-junction complex (EJC). It is 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. DDX39B may undergo several rounds of ATP hydrolysis during TREX assembly, driving the subsequent loading of components such as ALYREF/THOC and CHTOP onto mRNA. It also associates with pre-mRNA independently of ALYREF/THOC4 and the THO complex. DDX39B is involved in the nuclear export of intronless mRNA. The ATP-bound form recruits export adapter ALYREF/THOC4 to intronless mRNA. Its ATPase activity is cooperatively stimulated by RNA and ALYREF/THOC4. ATP hydrolysis is thought to trigger dissociation from RNA, allowing the association of ALYREF/THOC4 and the NXF1-NXT1 heterodimer. DDX39B plays a role in transcription elongation and genome stability.
DDX39B is also known as BAT1, D6S81E, UAP56.
