Low resistance, large dimension entrance to the inner cavity of BK channels determined by changing side-chain volume.

ABSTRACT: Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels have the largest conductance (250-300 pS) of all K(+)-selective channels. Yet, the contributions of the various parts of the ion conduction pathway to the conductance are not known. Here, we examine the contribution of the entrance to the inner cavity to the large conductance. Residues at E321/E324 on each of the four α subunits encircle the entrance to the inner cavity. To determine if 321/324 is accessible from the inner conduction pathway, we measured single-channel current amplitudes before and after exposure and wash of thiol reagents to the intracellular side of E321C and E324C channels. MPA(-) increased currents and MTSET(+) decreased currents, with no difference between positions 321 and 324, indicating that side ch

SUBMITTER: Geng Y 

PROVIDER: S-EPMC3105516 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature