Structural properties of NcTOKA. (A) Nucleotide sequence of the full-length NcTOKA, along with the amino acid sequence of the longest open reading frame. Transmembrane segments are underlined, and P domains are bold and underlined. The asterisk represents the position of a 75-bp intron identified from the genomic DNA sequence. (B) Alignment of the P domains of NcTOKA and other K+ channels. Identical and similar residues are boxed in black and gray, respectively. The accession numbers are as follows: ScTOK1, P40310; ORK1, Q94526; AtKCO1, CAA65988; KCNK1, U76996; and KAT1, S32816. (C) Hydropathy profile and deduced topology for NcTOKA. Hydrophobicity values were calculated according to the method of Kyte and Doolittle (17a; unpublished data) (window size of 17 residues) and are plotted against amino acid position. The TMS and P domains are labeled.