Table 1.

The amino acid sequence of the pHLIP variants and K-pHLIP controls

Probe	Amino acid sequence
WT	ACEQNPIYWARYADWLFTTPLLLLDLALLVDADEGT
Var3	ACDDQNPWRAYLDLLFPTDTLLLDLLW
Var7	ACEEQNPWARYLEWLFPTETLLLEL
K-Var3	ACDDQNPWRAYLKLLFPTKTLLLKLLW
K-Var7	ACEEQNPWARYLKWLFPTKTLLLKL

The transmembrane protonatable D and E (underlined) residues in Var3 and Var7 were replaced by positively-charged K residues (also underlined) in K-Var3 and K-Var7, which prevents K-Var insertion into membrane and thus tumor targeting.