Fig. 5.

Hyperosmotic shock activates Yvc1p. (A) As depicted in Inset, a wild-type vacuole clamped at -20 mV and equilibrated at 0.4 osmolar was subjected to an osmotic upshock by the addition of 1.5 osmolar solution <1 cm away (arrowhead). Bath, 10^-5 M Ca²⁺. The vacuole shrank and showed the ≈400 pS activities within seconds. The conducting ions were held constant and the added osmoticum was sorbitol. (B) An amplitude-histogram analysis of 15 sec of current in A, beginning 6 sec after the arrowhead. Current amplitude distributes in bins of uniform increments, ruling out the response to the osmotic upshock being nonspecific artifacts of the patch.