Fig. 3.

Truncation of ProTα. a Primary structure of several truncated variants of ProTα-Cre. Deleted regions are shown in black. b Lipid-mediated delivery efficiency of Cre fused to each truncated ProTα variant into the BSR-TdTomato cell line. Removal of the central region containing stretches of acidic residues (B3, B5) results in a >100-fold reduction in protein delivery potency. Deletion of either the N-terminus or the C-terminus of ProTα (B4, B2) also reduces delivery efficiency, suggesting that the termini also play a role in the delivery process. EC₅₀ is defined as the protein concentration at which 50% of analyzed cells contain red fluorescence. Values and error bars represent the mean and standard deviation of three independent biological replicates performed on different days. EC₅₀ values were determined by nonlinear fit to the Hill equation, and are followed by the standard errors of the fit. Source data are available in the Source Data file