Interactions of the H5 pore region and hydroxylamine with N-type inactivation in the Shaker K+ channel.
Mutations at sites in the H5 region of the Shaker B K+ channel were used to analyze the influence of the pore on N-type inactivation. Single-channel and two-electrode voltage clamp analyses showed that mutations at residues T441 and T442, which are thought to lie at the internal mouth of the pore, produced opposite effects on inactivation: the inactivated state is stabilized by T441S and destabilized by T442S. In addition, an ammonium derivative, hydroxylamine (OH-(NH3)+), appears to bind in the pore region of T441S and further decreases the rate of recovery from N-type inactivation. This effect relies on the presence of the amino-terminal. The effect of hydroxylamine on the T441S mutation of this K+ channel shows several properties analogous to those of local anesthetics on the Na+ channel. These results can be interpreted to suggest that part of the H5 region contributes to the receptor for the inactivation particle and that a hydroxylamine ion trapped near that site can stabilize their interaction.
Yool
A J
AJ
Department of Physiology, University of Arizona, Tucson 85724.
Schwarz
T L
TL
D000818:Animals; D019811:Hydroxylamine; D006898:Hydroxylamines / Q000737:chemistry*; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009865:Oocytes; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000737:chemistry*; D011994:Recombinant Proteins; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
D006898:Hydroxylamines; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D011994:Recombinant Proteins; D019811:Hydroxylamine