Open AccessElectrostatic influences of charged inner pore residues on the conductance and gating of small conductance Ca 2+ activated K + channels
Author(s) -
Weiyan Li,
Richard W. Aldrich
Publication year - 2011
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.1103090108
Subject(s) - gating , conductance , biophysics , divalent , chemistry , calcium activated potassium channel , potassium channel , ion channel , membrane potential , inward rectifier potassium ion channel , intracellular , sk channel , rectification , biochemistry , physics , receptor , biology , voltage , organic chemistry , condensed matter physics , quantum mechanics
SK channels underlie important physiological functions by linking calcium signaling with neuronal excitability. Potassium currents through SK channels demonstrate inward rectification, which further reduces their small outward conductance. Although it has been generally attributed to block of outward current by intracellular divalent ions, we find that inward rectification is in fact an intrinsic property of SK channels independent of intracellular blockers. We identified three charged residues in the S6 transmembrane domain of SK channels near the inner mouth of the pore that collectively control the conductance and rectification through an electrostatic mechanism. Additionally, electrostatic contributions from these residues also play an important role in determining the intrinsic open probability of SK channels in the absence of Ca2+ , affecting the apparent Ca2+ affinity for activation.