Stefan H. Heinemann

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After removal of N-type inactivation in Shaker K channels another inactivation process remains (C-type inactivation). The C-type inactivation time course is reversibly slowed when external [K+] increases. The effect of K+ is mimicked by Rb+ and, with less potency, by the less permeant ions Na+, Cs+, and NH4+. These results, which can be explained by the(More)
From worm to man, many odorant signals are perceived by the binding of volatile ligands to odorant receptors that belong to the G-protein-coupled receptor (GPCR) family. They couple to heterotrimeric G-proteins, most of which induce cAMP production. This second messenger then activates cyclic-nucleotide-gated ion channels to depolarize the olfactory(More)
Structural and functional diversity of voltage-gated Kv1-type potassium channels in rat brain is enhanced by the association of two different types of subunits, the membrane-bound, poreforming alpha-subunits and a peripheral beta-subunit. We have cloned a beta-subunit (Kv beta 1) that is specifically expressed in the rat nervous system. Association of Kv(More)
The SS2 and adjacent regions of the 4 internal repeats of sodium channel II were subjected to single mutations involving, mainly, charged amino acid residues. These sodium channel mutants, expressed in Xenopus oocytes by microinjection of cDNA-derived mRNAs, were tested for sensitivity to tetrodotoxin and saxitoxin and for single-channel conductance. The(More)
The sodium channel, one of the family of structurally homologous voltage-gated ion channels, differs from other members, such as the calcium and the potassium channels, in its high selectivity for Na+. This selectivity presumably reflects a distinct structure of its ion-conducting pore. We have recently identified two clusters of predominantly negatively(More)
Modulation of neuronal excitability by regulation of K+ channels potentially plays a part in short-term memory but has not yet been studied at the molecular level. Regulation of K+ channels by protein phosphorylation and oxygen has been described for various tissues and cell types; regulation of fast-inactivating K+ channels mediating IK(A) currents has not(More)
1. The human eag-related potassium channel, HERG, gives rise to inwardly rectifying K+ currents when expressed in Xenopus oocytes. 2. The apparent inward rectification is caused by rapid inactivation. In extracellular Cs+ solutions, large outward currents can be recorded having an inactivation time constant at 0 mV of about 50 ms with an e-fold change every(More)
C-type inactivation of Shaker potassium channels involves entry into a state (or states) in which the inactivated channels appear nonconducting in physiological solutions. However, when Shaker channels, from which fast N-type inactivation has been removed by NH2-terminal deletions, are expressed in Xenopus oocytes and evaluated in inside-out patches,(More)
The rat homologue of Drosophila ether à gogo cDNA (rat eag) encodes voltage-activated potassium (K) channels with distinct activation properties. Using the Xenopus expression system, we examined the importance of extracellular Mg2+ on the activation of rat eag. Extracellular Mg2+ at physiological concentrations dramatically slowed the activation in a(More)
Cumulative oxidative damages to cell constituents are considered to contribute to aging and age-related diseases. The enzyme peptide methionine sulfoxide reductase A (MSRA) catalyzes the repair of oxidized methionine in proteins by reducing methionine sulfoxide back to methionine. However, whether MSRA plays a role in the aging process is poorly understood.(More)