DDX39B - Spliceosome RNA helicase DDX39B - human protein (Function)
 
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DDX39B »  Spliceosome RNA helicase DDX39B   [ EC 3.6.4.13 ]
 
Protein also known as:  HLA-B-associated transcript 1 protein.
Gene name:  DDX39B
Family name: DEAD box helicase » DECD
Entry whose protein(s) existence is based on evidence at protein level
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GENE REF ISO

Function

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Overview 
Involved in nuclear export of spliced and unspliced mRNA. Assembling component of the TREX complex which is thought 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 by a transcription-independent mechanism, binds to mRNA upstream of the exon-junction complex (EJC) and 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. May undergo several rounds of ATP hydrolysis during assembly of TREX to drive subsequent loading of components such as ALYREF/THOC and CHTOP onto mRNA. The TREX complex is essential for the export of Kaposi's sarcoma-associated herpesvirus (KSHV) intronless mRNAs and infectious virus production. Also associates with pre-mRNA independent of ALYREF/THOC4 and the THO complex. Involved in the nuclear export of intronless mRNA; the ATP-bound form is proposed to recruit export adapter ALYREF/THOC4 to intronless mRNA; its ATPase activity is cooperatively stimulated by RNA and ALYREF/THOC4 and ATP hydrolysis is thought to trigger the dissociation from RNA to allow the association of ALYREF/THOC4 and the NXF1-NXT1 heterodimer. Involved in transcription elongation and genome stability.  
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  • CuratedUniProtKB
Splice factor that is required for the first ATP-dependent step in spliceosome assembly and for the interaction of U2 snRNP with the branchpoint. Has both RNA-stimulated ATP binding/hydrolysis activity and ATP-dependent RNA unwinding activity. Even with the stimulation of RNA, the ATPase activity is weak. Can only hydrolyze ATP but not other NTPs. The RNA stimulation of ATPase activity does not have a strong preference for the sequence and length of the RNA. However, ssRNA stimulates the ATPase activity much more strongly than dsRNA. Can unwind 5' or 3' overhangs or blunt end RNA duplexes in vitro. The ATPase and helicase activities are not influenced by U2AF2; the effect of ALYREF/THOC4 is reported conflictingly with [PubMed23299939] reporting a stimulatory effect.  
13
  • CuratedUniProtKB
According to TCDB this is a transporter from family:
the nuclear mrna exporter (mrna-e) family  3.A.18.1.1  
GO molecular function 
ATP bindingdefinition[GO:0005524]  
  • IEAUniProtKB KW
ATP-dependent protein bindingdefinition[GO:0043008]  
1
  • IDABHF-UCL
ATP-dependent RNA helicase activitydefinition[GO:0004004]  
2
  • IDABHF-UCL
  • IDAUniProtKB
Protein bindingdefinition[GO:0005515]  
4
  • IPIUniProtKB
RNA-dependent ATPase activitydefinition[GO:0008186]  
1
  • IDAUniProtKB
U4 snRNA bindingdefinition[GO:0030621]  
1
  • IDABHF-UCL
U6 snRNA bindingdefinition[GO:0017070]  
1
  • IDABHF-UCL
GO biological process 
ATP catabolic processdefinition[GO:0006200]  
3
  • IDAGOC
mRNA export from nucleusdefinition[GO:0006406]  
2
  • IDAUniProtKB
mRNA splicing, via spliceosomedefinition[GO:0000398]  
1
  • IGIUniProtKB
Negative regulation of DNA damage checkpointdefinition[GO:2000002]  
1
  • IMPUniProtKB
Positive regulation of DNA-templated transcription, elongationdefinition[GO:0032786]  
1
  • IMPUniProtKB
RNA secondary structure unwindingdefinition[GO:0010501]  
1
  • IDABHF-UCL
RNA splicingdefinition[GO:0008380]  
1
  • IDABHF-UCL
Spliceosomal complex assemblydefinition[GO:0000245]  
1
  • IDABHF-UCL
Viral mRNA export from host cell nucleusdefinition[GO:0046784]  
1
  • IDAUniProtKB
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 3.6.4.13: ATP + H(2)O ADP + phosphate.  
1
  • CuratedUniProtKB
Pathways 
According to KEGG, this protein belongs to the following pathways:
Influenza A  hsa05164+7919  
mRNA surveillance pathway  hsa03015+7919  
RNA transport  hsa03013+7919  
Spliceosome  hsa03040+7919  
 

Biophysicochemical properties

Kinetic parameters
KM 3.3 uM for ATP
Vmax 0.126 uM/min/mg enzyme with ATP as substrate

Keywords

Biological process 
Transport  definition   [KW-0813]
mRNA processing  definition   [KW-0507]
mRNA splicing  definition   [KW-0508]
mRNA transport  definition   [KW-0509]
Molecular function 
Helicase  definition   [KW-0347]
Hydrolase  definition   [KW-0378]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

GeneWiki: BAT1
GenomeRNAi: 7919
PRO: PR:Q13838