Table 1 Structural and functional comparisons of the TmPiT and hPiT mutants.

*Values present percentage of wild type. †Pi uptake by hPiT mutants is abolished. ‡These variants are found in human patients with primary familial brain calcification (PFBC) disease.

TmPiT mutationsFunctional sitePi binding (this study)Pi uptake* (this study)hPiT mutations†hPiT PFBC variants‡ (10, 28)
D22ANa1/Pi binding22.5 μM4.7%D28N (20)D28N
D258ANa2/Pi binding27.8 μM18.9%D506N (20)
D22A/D258ANa1/Na2/Pi bindingn.d.
D327QNafore bindingn.d.E575Q (26)E575K
W378AConformational changen.d.W626 duplication
W139AMay be associated with conformational change7.2 mM