FIGURE 5.

Recombinant ATOM forms a high conductance channel with a characteristic gating behavior setting it apart from Tom40. A current trace of a lipid bilayer containing a single ATOM channel is displayed (left panel; same as in Fig. 2A). As indicated by dashed lines, complete closure of the channel occurs in three distinct steps, each representing an independent pore. In the case of recombinant Tom40 (right panel), an active single channel unit consists of one pore (dashed lines), closing for longer periods in one step at voltages above ±80 mV and apart from that displaying fast flickering into a subconductance state or the closed state. The lower panel illustrates the gating behavior of a single pore by enlargement of the sections highlighted in gray in the upper current traces. Buffer conditions were symmetric with 250 mm KCl, 10 mm MOPS/Tris, pH 7, in cis and trans.