... side-chain protecting groups of sPi4 trifunctional residues were:tert-butyl (t-Bu) for Ser, Thr, Tyr, Asp, and Glu; trityl (Trt) for Cys, Asn, and Gln; pentamethylchroman (Pmc) for Arg, and tert-butyloxycarbonyl ... thesidechains of Glu332 of each rat Kv1.2 a-subunit(Kv1.2 channel is composed of four a-subunits) and Arg10, Arg19, Lys30 and Lys33 of Pi4. The Lys26 sidechain of Pi4 enters into the ion channel pore and ... atoms of the P-domainselectivity filter. Residue Tyr35 of Pi4 is involved in ahydrophobic cluster of aromatic residues consisting of Trp344, from one of the four Kv1.2 a-subunits, and Trp345and...