TABLE 1

Functional characterization of the rOCT1(10ΔC) and rOCT1(10ΔC-F483C) in comparison with rOCT1 wild type

Wild-type rOCT1, rOCT1(10ΔC), or rOCT1(10ΔC-F483C) were expressed in oocytes, and concentration activation curves of [14C]TEA uptake, [3H]MPP uptake, TEA-induced currents at −50 mV, and choline-induced currents at −50 mV were measured using 8 to 10 different substrate concentrations. Vmax, Imax, I0.5, and Km values were determined by fitting the Michaelis-Menten equation to the data of individual experiments. Mean values ± S.E. are presented. The number of experiments is shown in parentheses.


Activity

Wild Type

10ΔC

10ΔC-F483C
[14C]TEA uptake
Vmax (pmol · oocyte−1 · h−1) 503 ± 73 (4) 560 ± 95 (3) 385 ± 68 (4)
Km (μM) 52 ± 21 (11) 67 ± 8 (3) 143 ± 27 (3)***,†††
[3H]MPP uptake
Vmax (pmol · oocyte−1 · h−1) 122 ± 30 (5) 133 ± 23 (3) 57 ± 9 (4)
Km (μM) 3.9 ± 1.1 (3) 2.5 ± 1.0 (2) 3.0 ± 0.7 (3)
TEA induced current
Imax (nA) 6.4 ± 2.3 (5)a 15.3 ± 1.7 (4)* 9.2 ± 4.1 (3)
K0.5 (μM) 30 ± 3 (5)a 54 ± 5 (4) 118 ± 8 (3)**,
Choline-induced current
Imax (nA) 18 ± 13 (46)a 43 ± 11 (9)*,a 25 ± 3.4 (10)
K0.5M)
290 ± 180 (6)a
1410 ± 240 (3)***,a
1300 ± 160 (10)***
  • * P < 0.05,

  • ** P < 0.01, and

  • *** P < 0.001 compared with wild-type rOCT1.

  • P < 0.05,

  • ††† P < 0.001 compared with rOCT1(10ΔC).

  • a Data reported previously (Sturm et al., 2007).