Table 1.

Overview of human NaPi-IIa constructs

Transmembrane Segment	Construct	Expression		Transport Function		Kinetics
		WB	IC	32Pi	TEVC	Steady State	Pre-Steady State
	WT	+	+	+	1.0	+	+
TM2	T200A	+	+	+	0.14 ± 0.02	+	−
	Q206A	ND	ND	ND	0.35 ± 0.05	+	+
	Q206N	ND	ND	ND	0.79 ± 0.09	+	+
	D209A	ND	ND	ND	0.35 ± 0.05	+	+
	D209E	ND	ND	ND	1.11 ± 0.14	+	+
	R210A	ND	ND	+	0.37 ± 0.04	+	+
	T211A	ND	ND	ND	1.14 ± 0.01	+	+
TM3	N227A	+	+	ND	ND	−	ND
	N227Qa	+	ND	+	+	+	ND
TM5	S447A	+	+	+	0.58 ± 0.13	+	+
	N448A	+	+	−	−	−	−
	T451A	+	+	−	−	−	+
	T454A	+	+	−	−	−	+

For TEVC transport function, values indicate mean ± SE fraction of P_i-induced current at −60 mV relative to WT for n >5 cells per construct. WB, western blot (total oocyte lysate); IC, immunocytochemistry; +, experimental verification; −, undetected/unresolved; ND, not done.

^aSee Virkki et al. (6).