Fig. 1

A mechanically activated current permeable to Ca²⁺ is present at the plasma membrane. a Representative membrane patches from Col-0 (left) and an msl quintuple mutant msl4;msl5;msl6;msl9;msl10 (mslΔ5, right), exposed to increased positive pressure steps in an outside-out patch configuration show a rapidly activated, rapidly inactivated current in ionic conditions favorable for Ca²⁺ current recording. We have named the channel responsible for this activity the RMA channel (see text). Time constants are means ± SE (n = 6); b Under the same conditions, single channel I/V curves show similar RMA channel conductance in Col-0 (solid square) and in the mslΔ5 mutant (open square). Values are means ± SE (n = 6); c Representative single channel recordings showing that the RMA current is reversibly eliminated by exchanging Ca²⁺ ions with non-permeant TEA⁺ ions. d Open probability (for n channels, (nP(o)) is severely decreased in TEA⁺ bath solution. A paired t-test was used to compare means (**P < 0.01). Values are means ± SE. For all experiments, the membrane potential was held at −196 mV. Ionic conditions are described in the Methods section