Exon 16 was replaced with a modified exon 16 in which nucleotide substitutions result in the amino acid substitution of alanine for leucine at position 502 (L502A) in the conserved carboxy-terminal (CCT) domain. Flp-mediated recombination removed an FRT-flanked puromycin cassette inserted in intron 15. This mutation suppresses protein phosphorylation by WNK isoforms and results in markedly reduced phosphorylation and expression of sodium ion co-transporters NCC and NKCC2 in the kidney. (J:224087)