TABLE 2.

Single-channel kinetics of ROMK and pH-gate mutants (low pH)

	ROMK	L160A	L160G	L160G-I163M
Open probability	0.93 ± 0.01(3)	0.93 ± 0.01 (5)	0.94 ± 0.01 (3)	0.89 ± 0.01 (4)
Open time (ms)	18.8 ± 3 (3)	20.1 ± 2 (5)	25.2 ± 8 (3)	12.0 ± 2 (4)
Closed time (ms)	1.3 ± 0.1 (3)	0.8 ± 0.1 (5)	1.2 ± 0.2 (3)	1.2 ± 0.2 (4)

Same conditions as for Table 1, except that the pH of the permeant buffer bath was 6.6 instead of 8. ROMK and L160A kinetics were determined 1 min before channel shutdown. The kinetics of L160G and L160G-I163M were determined after 10 min at low pH. There were no significant differences in kinetic parameters among ROMK, L160A, and L160G (P > 0.05). Furthermore, within each clone, there were no significant kinetic differences at low pH versus high pH (P > 0.05) (see Table 1).