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MOLECULAR-BASIS OF ALTERED EXCITABILITY IN SHAKER MUTANTS OF DROSOPHILA-MELANOGASTER

LICHTINGHAGEN, R; STOCKER, M; WITTKA, R; BOHEIM, G; STUHMER, W; FERRUS, A; PONGS, O; (1990) MOLECULAR-BASIS OF ALTERED EXCITABILITY IN SHAKER MUTANTS OF DROSOPHILA-MELANOGASTER. EMBO J , 9 (13) 4399 - 4407.

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Abstract

Mutations in the Shaker (Sh) locus of Drosophila melanogaster have differing effects on action potential duration and repolarization in neurons as well as on A-type K+ channels (I(A)) in muscle. The molecular basis of three exemplary Sh alleles (Sh(KS133), Sh(E62) and Sh5) has been identified. They are point mutation in the Sh transcription unit expressing aberrant voltage-gated A-type K+ channels. Replicas of each mutation have been introduced by in vitro mutagenesis into Sh cDNA. The expression of in vitro transcribed mutant Sh cRNA in Xenopus laevis oocytes reproduced the specific phenotypic traits of each Sh allele. The lack of I(A) in Sh(KS133) is due to a missense mutation within a sequence motif occurring in all hitherto characterized voltage-gated K+ channel forming proteins. The reduction of I(A) in Sh(E62) is due to a mutation in an AG acceptor site. The intervening sequence between exon 19 and 20 is not spliced in Sh(E62) RNA. As a consequence Sh(E62) flies do not contain the full complement of Sh K+ forming proteins. Finally, the Sh5 mutation leads to an altered voltage dependence of K+ channel activation and inactivation as well as to an accelerated rate of recovery from inactivation. This is due to a missense mutation altering the amino acid sequence of the proposed transmembrane segment S5 of the Sh K+ channels. Segment S5 is located adjacently to the presumed voltage sensor of voltage-gated ion channels. The results explain the altered properties of excitable cells in Sh mutants and provide a general model for the possible role of A-type K+ channels in modulation action potential profiles.

Type: Article
Title: MOLECULAR-BASIS OF ALTERED EXCITABILITY IN SHAKER MUTANTS OF DROSOPHILA-MELANOGASTER
Keywords: ACTION POTENTIAL, A-CURRENT, SPLICING, POTASSIUM CHANNEL, DELAYED RECTIFIER PROPERTIES, VOLTAGE-CLAMP ANALYSIS, PRE-MESSENGER RNA, POTASSIUM-CHANNEL, ACTION-POTENTIALS, XENOPUS OOCYTES, RAT-BRAIN, LOCUS, GENE, CDNA
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Neuro, Physiology and Pharmacology
URI: http://discovery.ucl.ac.uk/id/eprint/492244
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