甲型流感病毒非结构蛋白NS2亲核信号序列的初步研究

THE NUCLEAR LOCATION SIGNALS IN THE INFLUENZA A VIRUS NS2 NONSTRUCTURAL PROTEIN

Influenza a virus NS2 nonstructural protein,expressed alone in eucar yotic cells, enters and accumulates in the nucleus. So the NS2 proteincontains the sequences which determine the nuclear location of NS2-----the nuclear location signal(NLS) . To define the NLSs of NS2, a series of recombinant SV40 vectors that express NS2 mutants with different lenths of deletion was constructed. Analysis of the subcellular locations of the different NS2 proteins expressed in COS-1 cells by immunof luore scence staining resulted in the discovery that the amino acids 60 to 82 of NS2 are related to nuclear location. According to comparative analysis it was suggested that NS2 may contain two functionally different NLSs. The NLSl contains a stretch of charged amino acids E-K-W-R-E( amino acids 63 to 67 ) . This sequence is responsible for the nuclear envelope binding of NS2. The NLS2 is defined within the region between amino acids 68 and 82. This domain is necessary for the nuclear accumunation of NS2.