Fig. 4: Diverse field and laboratory-derived isoforms of PfCRT transport the VF-6 peptide.

a The VF-6 transport activities, including kinetic parameters, of various field and laboratory-derived PfCRT isoforms in Xenopus oocytes (K_m, Michaelis–Menten constant; V_max, maximum velocity). b The capacity of PfCRT to transport VF-6 decays exponentially as the protein’s CQ transport activity increases (R² = 0.93). Exceptions to this trend include PfCRT^Cam734, L272F-PfCRT^Dd2, L272F-PfCRT^3D7 and C101F-PfCRT^Dd2. c [³H]CQ transport (left) and [³H]VF-6 transport (right) via epitope-tagged versions of PfCRT^3D7 and PfCRT^Dd2. The version of PfCRT^Dd2 carrying a C-terminal 3xmyc tag does not mediate [³H]CQ transport. The other four variants of PfCRT^Dd2 retain all or most of their CQ transport activity. By contrast, none of the tagged versions of PfCRT^3D7 or PfCRT^Dd2 transport [³H]VF-6. The fusion of polypeptides to PfCRT can therefore abolish its ability to transport peptides, even when the protein remains able to transport CQ. The data are the mean of n = 5 independent experiments (each yielding similar results and overlaid as individual data points in a and c), and the error is the SEM. Where not visible, the error bars fall within the symbols. The asterisks denote a significant difference from the relevant PfCRT^Dd2 (red asterisks) or PfCRT^3D7 (blue asterisks) control; *P < 0.05, **P < 0.01, ***P < 0.001 (one-way ANOVA). The source datasets are provided as a Source Data file.