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Voltage-gated potassium channels are critical elements in providing functional diversity in nervous systems. The diversity of voltage-gated K+ channels in modern triploblastic metazoans (such as mollusks, arthropods and vertebrates) is provided primarily by four gene subfamilies (Shaker, Shal, Shab, and Shaw), but there has been no data from the ancient(More)
The S4 segment of the jellyfish (Polyorchis penicillatus) Shaker channel jShak1 contains only six positively charged motifs. All other Shaker channels, including the jellyfish Shaker channel jShak2, have seven charges in this segment. Despite their charge differences, both these jellyfish channels produce currents with activation and inactivation curves(More)
omega-Conotoxin TxVII is the first conotoxin reported to block L-type currents. In contrast to other omega-conotoxins, its sequence is characterized by net negative charge and high hydrophobicity, although it retains the omega-conotoxin cysteine framework. In order to obtain structural information and to supply material for further characterization of its(More)
Calcium (Ca2+) channel clustering at specific presynaptic sites is a hallmark of mature synapses. However, the spatial distribution patterns of Ca2+ channels at newly formed synapses have not yet been demonstrated. Similarly, it is unclear whether Ca2+ 'hotspots' often observed at the presynaptic sites are indeed target cell contact specific and represent a(More)
The jellyfish gene, jShak2, coded for a potassium channel that showed increased conductance and a decreased inactivation rate as [K(+)](out) was increased. The relative modulatory effectiveness of K(+), Rb(+), Cs(+), and Na(+) indicated that a weak-field-strength site is present. Cysteine substituted mutants (L369C and F370C) of an N-terminal truncated(More)
The amplitude of an A-like potassium current (I(Kfast)) in identified cultured motor neurons isolated from the jellyfish Polyorchis penicillatus was found to be strongly modulated by extracellular potassium ([K(+)](out)). When expressed in Xenopus oocytes, two jellyfish Shaker-like genes, jShak1 and jShak2, coding for potassium channels, exhibited similar(More)
Small wounds (1.2 mm in diameter) made in the sheet of myoepithelial cells forming the "swimming" muscle of the jellyfish, Polyorchis penicillatus, were closed within 10 h by epithelial cells migrating centripetally to the wound center. Some 24 to 48 h later these cells redifferentiated into fully contractile muscle cells. Labeling with bromodeoxyuridine(More)
1. Whole cell voltage-clamp recordings from isolated swimming motor neurons (SMNs) reveal a rapidly activating and inactivating sodium current. 2. Permeability ratios of PLi/PNa = 0.941 and P(guanidinium)/PNa = 0.124 were measured for the mediating channel, which was impermeable to rubidium. 3. The conductance/voltage and steady state inactivation curves(More)
1. When jellyfish Shaker potassium channels (jShak2) are heterologously expressed in Xenopus oocytes at different levels they demonstrate density-dependent changes in electrical and kinetic properties of macroscopic currents. 2. The activation and inactivation properties of jShak2 channels depend on the extracellular potassium concentration. In this study(More)
1. At different levels of the holding potential on neuron R2 membrane in the Aplysia depilans abdominal ganglion, dopamine injected intracellularly increases the amplitude of both inward and outward currents recorded in response to the application of acetylcholine (ACh) to the ganglion surface. 2. The addition of dopamine to the external perfused solution(More)