TY - JOUR
T1 - Sulfhydryl modification inhibits K+ (M) current with kinetics close to acetylcholine in rodent NG108-15 cells
AU - Egorova, Alla
AU - Hoshi, Naoto
AU - Knijnik, Rimma
AU - Shahidullah, Mohammad
AU - Hashii, Minako
AU - Noda, Mami
AU - Higashida, Haruhiro
PY - 1997/3/25
Y1 - 1997/3/25
N2 - The effects of sulfhydryl reagents on M-type voltage-dependent potassium currents (I(K(M))) were examined in NG108-15 cells transformed to express ml muscarinic acetylcholine receptors (mAChRs), a NGPM1-27 clone. Focal application of glutathione at millimolar concentrations dissolved in acidic solutions caused a transient inward current in NGPM1-27 cells at holding potentials of -30 mV, associated with an inhibition of I(K(M)). The glutathione-induced response was mimicked by cysteine. These effects were also reproduced by superfusion with micromolar concentrations of HgCl2, AgNO3, N-methylmaleimide and p-chloromercuribenzoic acid (pCMB), agents which target protein thiols. Glutathione, HgCl2, AgNO3 and pCMB inhibited the peak conductance of I(K(M)) without shifting the half activating voltage (V(1/2)), which was comparable to the acetylcholine (ACh)-induced response. The voltage dependence of time constants for I(K(M)) deactivation in sulfhydryl reagent-, ACh- and non-treated cells resembled, but differed from that in Ba2+-treated cells. These results reveal that there is an accessible cysteine moiety, but not a disulfide bond, either on the M channel protein itself or on a protein directly involved in agonist-M channel coupling.
AB - The effects of sulfhydryl reagents on M-type voltage-dependent potassium currents (I(K(M))) were examined in NG108-15 cells transformed to express ml muscarinic acetylcholine receptors (mAChRs), a NGPM1-27 clone. Focal application of glutathione at millimolar concentrations dissolved in acidic solutions caused a transient inward current in NGPM1-27 cells at holding potentials of -30 mV, associated with an inhibition of I(K(M)). The glutathione-induced response was mimicked by cysteine. These effects were also reproduced by superfusion with micromolar concentrations of HgCl2, AgNO3, N-methylmaleimide and p-chloromercuribenzoic acid (pCMB), agents which target protein thiols. Glutathione, HgCl2, AgNO3 and pCMB inhibited the peak conductance of I(K(M)) without shifting the half activating voltage (V(1/2)), which was comparable to the acetylcholine (ACh)-induced response. The voltage dependence of time constants for I(K(M)) deactivation in sulfhydryl reagent-, ACh- and non-treated cells resembled, but differed from that in Ba2+-treated cells. These results reveal that there is an accessible cysteine moiety, but not a disulfide bond, either on the M channel protein itself or on a protein directly involved in agonist-M channel coupling.
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U2 - 10.1016/S0168-0102(96)01130-3
DO - 10.1016/S0168-0102(96)01130-3
M3 - Article
C2 - 9089697
AN - SCOPUS:0030889059
VL - 27
SP - 35
EP - 44
JO - Neuroscience Research
JF - Neuroscience Research
SN - 0168-0102
IS - 1
ER -