Impact of Y268 for experimental DHA and N-AT effects. Experimental mutation of tyrosine hY278 (xY268) impairs the ability of the PUFA DHA (left) but not the PUFA analogue N-AT (right) to shift V₅₀ of KCNQ1. Data shown as mean ± SEM; n = 3–7 per data point. Concentration-response curves were fitted using Eq. 2 with the Hill coefficient constrained to −1 (see Materials and methods for details).