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DDX3
a multifunctional DEAD box family RNA helicase with diverse cellular functions. DEAD box proteins are characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD), and are involved in several steps of gene expression, such as transcription, maturation of nuclear and mitochondrial mRNA, mRNA export, translation initiation, and ribosome and spliceosome assembly. DDX3 is required for nuclear export of HIV-1 viral transcripts, possibly in a complex with the viral Rev protein and host cofactor CRM1. DDX3 is required for hepatitis C virus (HCV) RNA replication and its expression is downregulated in hepatitis B virus (HBV) associated hepatocellular carcinoma (HCC). May function as a tumor suppressor protein. Its expression inhibits tumor cell colony formation and increases expression of the cdk inhibitor p21 Waf1/Cip1. Low DDX3 expression has been shown in HCC, and aberrant subcellular localization occurs in many squamous cell carcinomas. Reduced DDX3 expression in cultured cells causes a diminished dependence on serum for cell proliferation and changes in cyclin D1 and p21 Waf1/Cip1 expression. Associates with eIF4F to promote translation of selected mRNAs. Is phosphorylated by the mitotic cyclin dependent kinase, cyclin B/cdc2. This phosphorylation may cause a loss of DDX3 function and a concomitant repression of ribosome biogenesis and translation in mitosis. Involved in TBK1 and IKBKE-dependent IRF3 activation leading to IFN-beta induction. Involved in regulation of apoptosis. May be required for activation of the intrinsic but inhibit activation of the extrinsic apoptotic pathway. Regulated by the cell cycle. Maximally expressed in the cytoplasm during G1/S phase and decreased expression during G2/M phase. Located predominantly in nuclear speckles and, at low levels, throughout the cytoplasm. Associates with the outer side of nuclear pore complexes (NPC) and mitochondrial outer membranes. Shuttles between the nucleus and the cytoplasm in an exportin1-dependent manner. Associates with polyadenylated mRNAs in the cytoplasm and the nucleus. Predominantly located in nucleus during G0 phase and in the cytoplasm during G1/S phase. Belongs to the DEAD box helicase family, DDX3 subfamily. Two isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
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| Protein type: Cell cycle regulation; EC 3.6.4.13; Tumor suppressor; Translation initiation; Helicase; EC 3.6.1.- |
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Cellular Component: eukaryotic translation initiation factor 3 complex; mitochondrial outer membrane; stress granule; cytoplasm; nuclear speck; nucleus
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Molecular Function: RNA binding; ATPase activity; transcription factor binding; poly(A) binding; ATP-dependent DNA helicase activity; protein binding; DNA binding; translation initiation factor binding; eukaryotic initiation factor 4E binding; mRNA 5'-UTR binding; ATP-dependent RNA helicase activity; ATP binding; ribosomal small subunit binding
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Biological Process: ATP catabolic process; stress granule assembly; positive regulation of translation; transcription, DNA-dependent; positive regulation of apoptosis; response to virus; protein kinase cascade; positive regulation of caspase activity; negative regulation of caspase activity; positive regulation of cell growth; chromosome segregation; positive regulation of translational initiation; induction of apoptosis via death domain receptors; negative regulation of translation; RNA secondary structure unwinding; virus-host interaction; positive regulation of interferon-beta production; innate immune response; positive regulation of transcription from RNA polymerase II promoter; negative regulation of cell growth; negative regulation of protein complex assembly; mature ribosome assembly; negative regulation of apoptosis
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Reference #:
O00571 (UniProtKB)
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| Alt. Names/Synonyms: ATP-dependent RNA helicase DDX3X; CAP-Rf; DBX; DDX14; DDX3; DDX3X; DEAD (Asp-Glu-Ala-Asp) box polypeptide 3, X-linked; DEAD box protein 3, X-chromosomal; DEAD box, X isoform; DEAD/H (Asp-Glu-Ala-Asp/His) box polypeptide 3; DEAD/H box-3; helicase like protein 2; Helicase-like protein 2; HLP2 |
| Gene Symbols: DDX3X |
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Molecular weight: 73,243 Da
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Basal Isoelectric point: 6.73
Predict pI for various phosphorylation states
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Protein-Specific Antibodies or siRNAs from Cell Signaling Technology®
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