. 2011 Dec 7;302(9):C1293–C1305. doi: 10.1152/ajpcell.00397.2011

Table 2.

Summary of mutant hSGLT1 kinetics

	K_0.5^αMDG, mM	K_0.5^Na, mM	Turnover (I_max/Q_max), s⁻¹	K_i^Pz, μM	Q_max, nC	I_max, nA
hSGLT1	0.3–0.49	20–40	57	0.22	≈10	500–1,000
Sugar binding
H83C	>100	66^*	>>> 70	4 ± 1	6 ± 3	165 ± 21
E102C	>100	nm	nm	nm	nm	37 ± 11
W291C	>100	46^*	>>> 22 ± 5	68 ± 15	8 ± 2.0	177 ± 57
K321C	43 ± 10^†	76 ± 14^‡	nm	850 ± 50^‡	nm	nm
Q457C	13 ± 2	34 ± 2	49 ± 5	6 ± 1	6 ± 1	378 ± 60
N78A/C	6 ± 1	18 ± 1	>56 ± 7	4 ± 2	0.9 ± 0.2	68 ± 17
Na⁺ binding
S392A/C⁽³⁾	>100	66^*	>>>81 ± 6	4 ± 1	8 ± 1	264 ± 39
S393A/C⁽³⁾	4 ± 1	32 ± 3	56 ± 10	0.5 ± 0.2	2 ± 1	83 ± 15
Outer gates
L87C	6 ± 1	23 ± 1	>75 ± 8	1.2 ± 0.1	2 ± 1	165 ± 21
F101C	1.1 ± 0.2	9 ± 1	>>>107 ± 14	37 ± 12	7 ± 2	1,067 ± 350
F453C	1.8 ± 0.2	21 ± 1	>>>127 ± 16	1.0 ± 0.3	6 ± 1	690 ± 40
Inner gate
Y290C	>100	46^*	>>100	36 ± 6	11 ± 1	565 ± 226

Kinetics are means ± SE of 3–9 oocytes from at least 2 donor frogs. Kinetic parameters [K_0.5^αMDG, half-saturation concentration of α-methyl-d-glucopyranoside (αMDG); K_0.5^Na, half-saturation concentration of Na⁺; K_i^Pz, inhibitory constant for phlorizin) were determined at a membrane potential of −50 mV.

K_0.5^Na values estimated from Na⁺ dependence of charge movement. Note that for the other mutants, estimates are similar for all 3 assays of K_0.5^Na (see methods).

^†

Rabbit K321C at −150 mV.

^‡

Rabbit K321C at −50 mV(34). §Mean of Ala and Cys mutants for S392 and S393.

I_max, maximal sugar-induced current; Q_max, maximal charge movement; nm, not measurable.