. 2009 Apr 20;284(25):17266–17280. doi: 10.1074/jbc.M109.009613

TABLE 5.

Comparison of hCNT1 and hCNT3 mutations

✓ indicates transporter was detected immunologically and/or by function at the cell surface; x indicates transporter was immunologically absent from the cell surface; WT indicates wild type-like functional activity; ? indicates no measurable transport activity because of retention in intracellular membranes; ND indicates not determined.

Mutation		Plasma membrane expression		Change in phenotype
hCNT1^a	hCNT3	hCNT1	hCNT3^b	hCNT1	hCNT3^c
D172N	D192N	✓	✓	WT	WT
E308Q	E329Q	✓	✓	Na⁺ and uridine kinetics	WT
E308D		✓		Uridine kinetics only
E308C		✓		ND
E322Q	E343Q	✓	✓	Na⁺ and uridine kinetics, uncoupled transport	Na⁺ and uridine kinetics, no H⁺ dependence, uncoupled transport
E322D	E343D	✓	✓	Na⁺ and uridine kinetics	Na⁺, H⁺, and uridine kinetics
E322C	E343C	✓	✓	ND	Na⁺, H⁺, and uridine kinetics, Na⁺:uridine stoichiometry
E338Q	E359Q	✓	✓	WT	WT
E389Q	E410Q	✓	✓	WT	WT
E413Q	E434Q	✓	✓	WT	WT
	E483Q		✓		WT
D482N	D503N	x	✓	?	WT
D482E		✓		WT
D482C		ND		?
E498Q	E519Q	x	✓	?	No functional activity
E498D	E519D	✓	✓	WT	H⁺ kinetics
E498C	E519C	ND	✓	?	Na⁺ and uridine kinetics, no H⁺-dependence, Na⁺:uridine stoichiometry
E532Q	E553Q	x	✓		WT
E532D		x
E532C		ND		?
D565N	D586N	✓	✓	WT	WT

^a Data are from Ref. (31).

^b Data are from Fig. 3.

^c Data are from Fig. 2 and Tables 1–4.