The MlotiK1 channel transports ions along the canonical conduction pore

Abstract 

Although the cyclic nucleotide-modulated potassium channel from Mesorhizobium loti, MlotiK1, is easily studied using a ⁸⁶Rb⁺ flux assay, its comparatively low activity raises serious concerns about the integrity of the purified protein. We investigated the pathway of uptake using a multi-pronged approach. First, we probed the conduction pathway using quaternary ammonium compounds known to block conduction in eukaryotic K⁺ channels. Second, we examined the effect of chemical modification of putative pore-lining residues. Our results are consistent with ions traversing MlotiK1 along a conduction pathway like that of the eukaryotic channels, but at a much slower rate.

Keywords: Cysteine modification, Quaternary ammonium, Polyamine, Potassium channel