DDX3X Antibody – Mouse Monoclonal

DEAD box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD), are putative RNA helicases. They are implicated in a number of cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly. Based on their distribution patterns, some members of this family are believed to be involved in embryogenesis, spermatogenesis, and cellular growth and division. This gene encodes a DEAD box protein, which interacts specifically with hepatitis C virus core protein resulting a change in intracellular location. This gene has a homolog located in the nonrecombining region of the Y chromosome. The protein sequence is 91% identical between this gene and the Y-linked homolog. Alternative splicing results in multiple transcript variants.

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

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 binding; ATP-dependent RNA helicase activity; 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; negative regulation of translation; RNA secondary structure unwinding; 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