Fig 3.
The apparent Ca2+ sensitivity of BK channels decreased as the number of active Ca-bowls was reduced from 4 to 0. (a–d) Representative recordings from single-channel patches after the coexpression of TEA-insensitive and Ca-bowl mutated subunits. TEAO (1.5 mM) was present. The stoichiometry of each channel (right diagrams) was deduced from the single-channel current amplitudes. (e) Representative recordings from a homotetrameric BK channel with mutated Ca-bowls in the absence of TEAO. Horizontal bar, 100 ms; vertical bar, 10 pA. +50 mV.