We have cloned a novel voltage-gated K channel, LKv1, in two species of leech. The properties of LKv1 expressed in transiently transfected HEK293 cells is that of a delayed rectifier current. LKv1 may be a major modulator of excitability in leech neurons, since antibody localization studies show that LKv1 is expressed in the soma and axons of all neurons in both the central and peripheral nervo...

The adenylate cyclase activity was analyzed in fetal, early postnatal and adult inner ears of the CBA/CBA mouse and also in approximately one month old inner ears from Shaker -1 and Shaker -2 mice. A comparison was made with the maturation of potassium levels in endolymph as investigated with the X-ray energy dispersive technique. Adenylate cyclase activity in the developing normal inner ear sh...

Voltage-gated ion channels have voltage sensors that move in response to changes in membrane potential. This movement regulates the gates that control access of ions to the permeation pathway. To study the coupling between voltage sensors and gates, we immobilize the voltage sensors, using a bifunctional photo-cross-linking reagent that can be attached to an introduced cysteine, and observe the...

It has been shown for a Shaker channel (H-4) that its NH2-terminal cytoplasmic domain may form a "ball and chain" structure, with the "chain" tethering the "ball" to the channel while the "ball" capable of binding to the channel in its open state and causing inactivation. Equivalent structures have not been identified in mammalian Shaker homologues. We studied the functional role of the NH2-ter...

Human ether-à-go-go-related gene (hERG, Kv11.1) potassium channels have unusually slow activation and deactivation kinetics. It has been suggested that, in fast-activating Shaker channels, a highly conserved Phe residue (F290) in the S2 segment forms a putative gating charge transfer center that interacts with S4 gating charges, i.e., R362 (R1) and K374 (K5), and catalyzes their movement across...

In this study, we perform the first genetic analysis of K+ currents in Drosophila embryonic neurons revealing the identity of the currents present. Unlike muscles, where the presence of Shaker is obvious, Shaker currents are not detectable in these neurons. In contrast, we show that Shal is as important in these neuronal cell bodies as Shaker is in muscles. Only three single-channel currents we...

Potassium ions are vital for maintaining functionality of K channels. In their absence, many K channel types enter a long-lasting defunct condition characterized by absence of conductance and drastic changes in gating current. We show that channels pass through a dilated condition with altered selectivity as they are becoming defunct. To characterize these abnormalities we examined gating and i...

KvLm, a novel bacterial depolarization-activated K(+) (Kv) channel isolated from the genome of Listeria monocytogenes, contains a voltage sensor module whose sequence deviates considerably from the consensus sequence of a Kv channel sensor in that only three out of eight conserved charged positions are present. Surprisingly, KvLm exhibits the steep dependence of the open channel probability on ...

In the preceding, accompanying article, we present models of the structure and voltage-dependent gating mechanism of the KvAP bacterial K+ channel that are based on three types of evidence: crystal structures of portions of the KvAP protein, theoretical modeling criteria for membrane proteins, and biophysical studies of the properties of native and mutated voltage-gated channels. Most of the la...

Control systems for shakers are necessary to remove both shaker dynamics as well as coupling effects between the shaker and the structure under test. Little attention has been given to shaker control for nonlinear structures. This paper presents the design, implementation and results of a shaker controller for a horizontal, cantilevered beam subjected to a non-uniform magnetic field. The object...