Fig. 1.
Experimental systems for studies of BLM tubule and cell membrane neck. (A) A BLM tubule (beige) is extended between two end-rings; the left one is the Teflon orifice of diameter D1, and the right one is the patch pipette with an opening of diameter D2. D1 varied from 100 to 200 μm; D2 varied from 1 to 100 μm. L is the length of the tubule. Lipid reservoirs are shown by red dots. Electrical conductance of the tubule G is measured by using left and right electrodes. The tubule wall conductance (leakage through the wall) is measured by using right and center electrodes. The rectangular outline shows the area from which fluorescent images (Fig. 2B) were taken. (B) A vesicle pinching off from a patch of cell membrane inside the patch pipette. The neck (beige) connects two rings (D1 and D2), formed presumably by protein coat on the vesicle and proteins associated with plasma membrane (dark red). Electrical conductance of the neck G and the vesicle capacitance Cv were calculated from changes of electrical admittance measured with in and out electrodes.