Helicase SKI2W is an enzyme that in humans is encoded by the SKIV2L gene. This enzyme is a human homologue of yeast SKI2, which may be involved in antiviral activity by blocking translation of poly(A) deficient mRNAs. The SKIV2L gene is located in the class III region of the major histocompatibility complex. 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. Identification of gene A novel human cDNA, homologous to the yeast gene SKI2, was identified in 1995. Researchers localised the corresponding gene to chromosome 6p.21. The SKIV2L gene, also known as SKI2W or Ski2-like RNA Helicase, spans 11Kb and contains 28 exons. Located between RD and RP1 gene in MHC III on the short arm of chromosome 6, it has 16 transcripts on Ensembl, 3 of which are protein coding. One of these proteins, SKI2W, has 1246 amino acids and a helicase binding domain between amino acids 319-475, and is thought to be involved in exosome RNA mediated RNA decay. The presence of the DEVH-box at position 423-426 within SKI2W infers that it is a member of the SF-II helicase family. The human protein was named SKI2W because of its similarity to yeast protein Ski2, which has highly homologous (nearly identical) regions at the helicase domain and the C terminal. SKIV2L transcripts are expressed in most, if not all, human tissue tested including spleen, thymus, small intestine, colon, heart, brain and liver. Function The majority of the eukaryotic genome is transcribed into RNA molecules, which generates pools of RNA that require processing and surveillance in order to control abundant and damaged material. The RNA exosome multiprotein complex performs this function and is dependent on cofactors. The exosome was initially discovered in yeast but is also present in higher eukaryotes. It has activity in both the nucleus and cytoplasm for normal mRNA decay and for RNA surveillance and quality control through nonsense mediated; non-stop and no-go decay. SKI2W is part of the tetraprotein ski complex which is an obligatory cytoplasmic cofactor of the RNA exosome and consists of SKI2W, TTC37 and 2 subunits of