Abstract
The electrical signalling properties of neurons originate largely from the gating properties of their ion channels. N-type inactivation of voltage-gated potassium (Kv) channels is the best-understood gating transition in ion channels, and occurs by a 'ball-and-chain' type mechanism. In this mechanism an N-terminal domain (inactivation gate), which is tethered to the cytoplasmic side of the ...
Abstract
The electrical signalling properties of neurons originate largely from the gating properties of their ion channels. N-type inactivation of voltage-gated potassium (Kv) channels is the best-understood gating transition in ion channels, and occurs by a 'ball-and-chain' type mechanism. In this mechanism an N-terminal domain (inactivation gate), which is tethered to the cytoplasmic side of the channel protein by a protease-cleavable chain, binds to its receptor at the inner vestibule of the channel, thereby physically blocking the pore. Even when synthesized as a peptide, ball domains restore inactivation in Kv channels whose inactivation domains have been deleted. Using high-resolution nuclear magnetic resonance (NMR) spectroscopy, we analysed the three-dimensional structure of the ball peptides from two rapidly inactivating mammalian K. channels (Raw3 (Kv3.4) and RCK4 (Kv1.4)). The inactivation peptide of Raw3 (Raw3-IP) has a compact structure that exposes two phosphorylation sites and allows the formation of an intramolecular disulphide bridge between two spatially close cysteine residues. Raw3-IP exhibits a characteristic surface charge pattern with a positively charged, a hydrophobic, and a negatively charged region. The RCK4 inactivation peptide (RCK4-IP) shows a similar spatial distribution of charged and uncharged regions, but is more flexible and less ordered in its amino-terminal part.
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