In the voltage-gated Shaker K channel, the probability of opening increases from 10 to nearly 1 over a range of <100 mV (Islas and Sigworth, 1999). This exquisite sensitivity to voltage is conferred by positively charged amino acid residues located in the S4 transmembrane segment. In response to membrane depolarization, the side chains of four S4 arginine residues (R1–R4) in each of the four c...

The voltage-gated proton channel Hv1 plays a critical role in the fast proton translocation that underlies a wide range of physiological functions, including the phagocytic respiratory burst, sperm motility, apoptosis, and metastatic cancer. Both voltage activation and proton conduction are carried out by a voltage-sensing domain (VSD) with strong similarity to canonical VSDs in voltage-depende...

The fourth transmembrane segment (S4) has been shown to function as a voltage sensor in voltage-gated channels. On membrane depolarization, a stretch of S4 moves outward and initiates a number of conformational changes that ultimately lead to channel opening. Conserved proline residues are in the middle of the S4 of motifs I and III in voltage-dependent Ca2+ channels. Because proline often intr...

We studied the effects of lidocaine (1-5 mg/liter) on the diastolic currents of sheep Purkinje fibers by the two-microelectrode voltage clamp technique to obtain additional information on how lidocaine decreases the slope of spontaneous diastolic depolarization of mammalian Purkinje fibers. During voltage clamps we measured both the magnitude and time course of activation and deactivation of th...

Mutations in the ClC-7/Ostm1 ion transporter lead to osteopetrosis and lysosomal storage disease. Its lysosomal localization hitherto precluded detailed functional characterization. Using a mutated ClC-7 that reaches the plasma membrane, we now show that both the aminoterminus and transmembrane span of the Ostm1 β-subunit are required for ClC-7 Cl(-)/H(+)-exchange, whereas the Ostm1 transmembra...

This paper investigates the parametric excitation of a micro-pipe conveying fluid suspended between two symmetric electrodes. Electrostatically actuated micro-pipes may become unstable when the exciting voltage is greater than the pull-in value. It is demonstrated that the parametric excitation of a micro-pipe by periodic (ac) voltages may have a stabilizing effect and permit an increase of the...

Neural signaling is based on the regulated timing and extent of channel opening; therefore, it is important to understand how ion channels open and close in response to neurotransmitters and intracellular messengers. Here, we examine this question for potassium channels, an extraordinarily diverse group of ion channels. Voltage-gated potassium (Kv) channels control action-potential waveforms an...