NLS (PKKKRKV) is a peptide derived from the 40 tumor antigen of the great ape virus (SV40 big T antigen), which is a method to enhance the nuclear portal in the research field of gene transfer.
SV40 large T antigen NLS, originating from Large T antigen residue 47 to 55, facilitates protein import into the cell nucleus. This peptide is specifically generated from Large T antigen residue 47 to 55.