Table 1. Incidences of TRPP2-dependent channels in apical and ciliary membranes.

membrane	PS	cell line
		wild type	TRPP2 KO	TRPM3 KO
ciliary	−	103 / 304 [19]	0 / 36 [19]	0 / 45
	+	77 / 259	0 / 28	ND
apical	−	1 / 22 [19]	ND	ND
	+	3 / 57	0 / 30	0 / 34

The presence or absence of active TRPP2 channels was assessed with the cilium or apical membrane patch exposed to 3 μM cytoplasmic Ca²⁺ and the voltage clamped to +40 mV. If no large-conductance channels were seen to open within 2 min, active TRPP2 channels were judged to be absent. Where indicated, pregnenolone sulfate was included in the external (pipette) solution at either 75 μM or 230 μM. PS, pregnenolone sulfate; KO, knockout; ND, not determined.