Fig. 8.

Elimination of putative Cl⁻-binding site L369 on L-WNK1-Δ11 increased the inhibitory effect on KCCs and the activating effect on NKCC1. Xenopus laevis oocytes were injected with 0.2 μg/μl of either KCC3a (A), KCC4 (B), KCC2a (C), or NKCC1 (D) cRNA alone or together with 0.1 μg/μl of L-WNK1-Δ11 or L-WNK1-Δ11 harboring the L369F mutation cRNA, as stated. ⁸⁶Rb⁺ uptake was assessed 48 h later in hypotonic conditions (110 and 155 mosmol/kgH₂O, respectively for KCCs and NKCC1). The pooled data from 4 different experiments are shown as percentage of the cotransporter activity, with means ± SE; n = 4 (10–15 oocytes per group, per experiment were tested). Significantly different from the uptake observed in control alone (*P < 0.001, **P < 0.01, by Student's t-test).