On the activation-inactivation coupling in Shaker potassium channels.
The 'ball-and-chain' model suggests the existence of a negative site which may attract the positively charged inactivation ball to occlude the pore when the channel is in the open state. For Shaker K+ channels, we propose that the state-dependent negative site be tryptophan-435, which becomes negatively charged after receiving an electron from tyrosine-445. The kinetic scheme for the channel's activation-inactivation coupling as derived from the YW-gated model resembles a successful 'scheme 8' proposed by Zagotta and Aldrich. Our model suggests that the final rapid voltage-independent transition to the open state is due to the deprotonation of tyrosine-445.
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Chemical Dynamics Corporation, Guilderland, NY 12084.
D004579:Electron Transport; D015640:Ion Channel Gating; D007700:Kinetics; D008956:Models, Chemical; D015221:Potassium Channels / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
D015221:Potassium Channels; D014443:Tyrosine