Cloning and functional analysis of tipE, a novel membrane protein that enhances drosophila para sodium channel function

Abstract

Voltage-dependent sodium channels are involved in the initiation and propagation of action potentials in many excitable cells. Here we report that tipE, a gene defined by a temperature-sensitive paralytic mutation in Drosophila, encodes a novel integral membrane protein that dramatically stimulates functional expression in Xenopus oocytes of the Drosophila sodium channel alpha subunit encoded by the paralytic (para) locus. Using a heat shock promoter to control tipE+ gene expression in transgenic flies, we demonstrate that tipE+ gene expression is required during pupal development to rescue adult paralysis. In addition, we demonstrate a role for the tipE gene product in adults.

A calcium switch for the functional coupling between α (hslo) and β subunits (KV, Caβ) of maxi K channels

“…This type of K channels is ~nformed by at least two subunits, the pore-forming a subunit [I] and a regulatory {$ subunit [2][3][4]. Unlike other voltage-dependent K channel is subunits (Kvis), which are cytoplasmic [5], the iS subunit of the MaxiK channel (Kv,c~l~) has two putative transmembrane regions [2] similar to the 'ripe pars sodium channel subunit [6]. We now demonstrate that intracellular calcium controls the functional coupling between iS and a subunits of the MaxiK channel complex, in a concentration range relevant to cellular excitation.…”

Synergistic interaction between two cockroach sodium channel mutations and a tobacco budworm sodium channel mutation in reducing channel sensitivity to a pyrethroid insecticide

“…To prepare cRNA for oocyte injection, plasmid DNA of KD1 or Drosophila tipE construct was linearized with NotI, which does not cut the insert, followed by in vitro transcription with T7 polymerase using the mMESSAGE mMACHINE kit (Ambion Inc., Austin, TX). According to Feng et al (1995) and Warmke et al (1997), a robust expression in Xenopus oocyte of sodium current is achieved by co-injection of Drosophila tipE and para cRNAs. Therefore, we co-injected healthy stage VI Xenopus oocytes with 1 ng of both Drosophila tipE and KD1 cRNAs.…”

Molecular basis of differential sensitivity of insect sodium channels to DCJW, a bioactive metabolite of the oxadiazine insecticide indoxacarb

“…For robust expression of the cockroach BgNa v sodium channels, BgNa v cRNA was coinjected into oocytes with cRNA of the auxiliary subunit of D. melanogaster sodium channels (tipE), which is known to enhance the expression of insect sodium channels in oocytes (Feng et al, 1995;Warmke et al, 1997).…”