Objective; To study the role of nucleocapsid protein in virus replication and cell signaling passway

and to observe the cellular localization of SARS - CoV nucleocapsid protein. Methods; The sequence of SARS - CoV nucleocapsid protein was analyzed by protein analysis programs to identify nuclear localization signals ( NLS); 293 cells were transfected by the pECFP - C1 recombinant plasmids which expressed fusion protein of enhanced green fluorescence protein(EGFP) and nucleocapsid protein. At 24

48

72 hours post transfection (p. t. )

the Green Fluorescent Proteins (GFP) were observed by fluorescence microscope. Results; By using PROS-ITE

we identified a nuclear localization signal sequence from amino acids 373 to 389 or from amino acids 374 to 390 in the nucleocapsid protein sequence. However

the analysis of PredictNLS server revealed that the nuclear localization signal region was located between amino acids 36 and 44. N1 protein( 1 - 187aa) was located in both cytoplasm and cell nucleu;N protein(1 -422aa) and N2 protein( 161 -422aa) were located in cytoplasms . Conclusion; The nuclear localization signal is likely to be located between amino acids 36 and 44 in SARS - CoV nucleocapsid protein.