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Werner syndrome ATP-dependent helicase also known as DNA helicase, RecQ-like type 3 is an enzyme that in humans is encoded by the WRN gene. WRN is a member of the RecQ Helicase family.〔 Helicase enzymes generally unwind and separate double-stranded DNA. These activities are necessary before DNA can be copied in preparation for cell division (DNA replication). Helicase enzymes are also critical for making a blueprint of a gene for protein production, a process called transcription. Further evidence suggests that Werner protein plays a critical role in repairing DNA. Overall, this protein helps maintain the structure and integrity of a person's DNA. The WRN gene is located on the short (p) arm of chromosome 8 between positions 12 and 11.2, from base pair 31,010,319 to base pair 31,150,818. == Structure and function == WRN is a member of the RecQ Helicase family. It is the only RecQ Helicase that contains 3' to 5' exonuclease activity. These exonuclease activities include degradation of recessed 3' ends and initiation of DNA degradation from a gap in dsDNA. WRN is important in reparation of double stranded breaks, nonhomologous end joining, and base excision repair. WRN may also be important in telomere maintenance and replication, especially the replication of the G-rich sequences. WRN is an oligomer that can act as a monomer when unwinding DNA, but as a dimer in solution or a tetramer when complexed with DNA, and has also been observed in tetrameric and hexameric forms. The diffusion of WRN has been measured to 1.62 at nucleoli. Orthologs of WRN have been found in a number of other organisms, including ''Drosohphila'', ''Xenopus'', and ''C. elegans''. WRN is important to genome stability, and cells with mutations to WRN are more susceptible to DNA damage and DNA breaks. The amino terminus of WRN is involved in both helicase and nuclease activities, while the carboxyl-terminus interacts with p53, an important tumor suppressor.〔 WRN may function as an exonuclease in DNA repair, recombination, or replication, as well as resolution of DNA secondary structures. It is involved in branch migration at Holliday junctions, and it interacts with other DNA replication intermediates. mRNA that codes for WRN has been identified in most human tissues. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Werner syndrome ATP-dependent helicase」の詳細全文を読む スポンサード リンク
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