NLS-RFA1-GFP rescues the nuclear localization of Rfa1 in rtt105∆ mutant cells. The wild type RFA1 gene was fused with an SV40 large T Antigen nuclear localization sequence (NLS) at its 5'-end and a GFP gene at its 3' end to obtain a construct, driven by the RFA1 promoter to express NLS-RFA1-GFP fusion protein. The engineered construct was then transformed into WT or rtt105∆ mutant yeast cells to replace its endogenous RFA1 expression. The resulting yeast cells were then visualized under microscope, and GFP signals enriched in the nuclei were scored. RFA1-GFP lacking the NLS sequence was transformed into rtt105∆ rfa1∆ mutant cells as a control. DAPI staining indicates nuclear DNA. 