Diagram of the WNK4 truncation constructs. The Δ symbol followed by a number indicates the amino acid in the WNK4 polypeptide sequence after which the COOH terminal of the protein was truncated. FL denotes FL protein. TAP, tandem affinity purification tag; AID?, predicted autoinhibitory domain; CC, coiled-coil; PHAII, stretch of acidic amino acids where PHAII-associated mutations are located; c-myc, myc epitope tag.