DDX3 Antibody – Rabbit Polyclonal

The protein encoded by this gene is a member of the large DEAD-box protein family, that is defined by the presence of the conserved Asp-Glu-Ala-Asp (DEAD) motif, and has ATP-dependent RNA helicase activity. This protein has been reported to display a high level of RNA-independent ATPase activity, and unlike most DEAD-box helicases, the ATPase activity is thought to be stimulated by both RNA and DNA. This protein has multiple conserved domains and is thought to play roles in both the nucleus and cytoplasm. Nuclear roles include transcriptional regulation, mRNP assembly, pre-mRNA splicing, and mRNA export. In the cytoplasm, this protein is thought to be involved in translation, cellular signaling, and viral replication. Misregulation of this gene has been implicated in tumorigenesis. This gene has a paralog located in the nonrecombining region of the Y chromosome. Pseudogenes sharing similarity to both this gene and the DDX3Y paralog are found on chromosome 4 and the X chromosome. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Oct 2014]

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.

Protein type: Helicase; EC 3.6.4.13; Spliceosome; Cell cycle regulation; Translation initiation; RNA-binding

Chromosomal Location of Human Ortholog: Xp11.3-p11.23

Cellular Component: eukaryotic translation initiation factor 3 complex; mitochondrial outer membrane; stress granule; cytoplasm; nuclear speck; nucleus

Molecular Function: GTPase activity; CTPase activity; RNA binding; ATPase activity; transcription factor binding; poly(A) binding; ATP-dependent DNA helicase activity; protein binding; DNA binding; translation initiation factor binding; nucleoside-triphosphatase activity; eukaryotic initiation factor 4E binding; mRNA 5'-UTR binding; ATP-dependent RNA helicase activity; ATP binding; ribosomal small subunit binding

Biological Process: stress granule assembly; positive regulation of viral genome replication; positive regulation of translation; transcription, DNA-dependent; viral reproduction; positive regulation of apoptosis; response to virus; positive regulation of caspase activity; negative regulation of caspase activity; positive regulation of cell growth; DNA duplex unwinding; chromosome segregation; positive regulation of translational initiation; induction of apoptosis via death domain receptors; RNA secondary structure unwinding; negative regulation of translation; 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

Disease: Mental Retardation, X-linked 102