HERG K-channels contribute to the repolarization of the cardiac action potential and display unique gating properties with slow activation kinetics in combination with a fast inactivation process. Previous work by Viloria et al. (Biophysical Journal 2000) has shown that in addition to the voltage sensor (S4), N-terminal sequences affect the voltage dependence of activation. Deletions in the N-terminal "proximal domain" (residues 135–366) shifted the voltage dependence of activation towards more hyperpolarizing potentials; this shift increased with larger deletions, which suggested that the entire proximal domain played a modulating role in the activation process of hERG. However, we did not observe a hyperpolarizing shift with a subtotal deletion (~200 residues) designed to preserve the local charge distribution (midpoint 0.3 ± 1.5 mV vs 1.8 ± 1.8 mV in wild type). Furthermore we observed a large shift (midpoint -42.9 ± 0.9 mV, n=17) with a charge reversal of a basic cluster approximately 50 amino acids upstream of the S1 segment. This indicates that only a short charged section within the proximal domain is involved in the hyperpolarizing shift of the channel activation gating. Overal, our results support the observation that the N-terminus modulates the activation process of hERG, but we propose that this results from the local electric field of a short charged section located proximal to the S1 segment.