Typical sets of currents are shown for N1–720 co-expressed with C721–988 (A), N1–868 co-expressed with C869–988 (B), N1–871 co-expressed with C872–988 (C), N1–878 co-expressed with C879–988 (D), N1–885 co-expressed with C886–988 (E) and N1–888 co-expressed with C889–988 (F). By comparison with the currents for N1–720 co-expressed with C721–988, which are close to WT in their characteristics, currents from the other co-expressions are either obviously mutant or quite small.