Variability among insect sodium channels revealed by selective neurotoxins

Moskowitz, Haim; Herrmann, Robert O.; Zlotkin, Eliahu; Gordon, Dalia

doi:10.1016/0965-1748(94)90118-x

Cited by 39 publications

(41 citation statements)

References 21 publications

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“…Moreover, AaIT4 is not only potent against insect, but competes with a-type and P-type mammal toxins (Loret et al, 1991). With different insects, it is known that exitatory and depressant toxins bind to different sites (Moskowitz et al, 1994). AaIT5 will be a good tool to study the mode of action of scorpion toxins at the molecular level.…”

Section: Dgyikrhdgckvtclindnycdtecxxeggxygyxyxvgfmentioning

confidence: 99%

Anti‐Insect Toxin 5 (Aalts) from Androctonus Australis

Nakagawa

Lee

Lehmberg

et al. 1997

European Journal of Biochemistry

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An insect-selective scorpion toxin (AaIT5) was purified from the venom of the North African scorpion Androctonus australis, and its amino acid sequence was determined by a combination of automated Edman degradation, electrospray-ionization mass spectrometry, and sequence alignment. This insect toxin is very potent against the tobacco budworm, Heliothis virescens (100% lethal dose < 1.8 yg/100 mg body mass) and shows a distinct insect specificity and various symptoms. It is not toxic to mice after subcutaneous injection. The molecular mass of this toxin is 6882Da and the amino acid sequence is similar to those of Androctonus australis anti-insect toxin 4 (AaIT4), Leiurus quinquestriatus depressant anti-insect toxins (LqhIT2, LqqIT2), and Buthotus judaicus depressant anti-insect toxin (BjIT2).

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Section: Dgyikrhdgckvtclindnycdtecxxeggxygyxyxvgfmentioning

confidence: 99%

Anti‐Insect Toxin 5 (Aalts) from Androctonus Australis

Nakagawa

Lee

Lehmberg

et al. 1997

European Journal of Biochemistry

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“…Insect synaptosomes (P 2 L preparation) were prepared from the central nervous system of adult locusts (Locusta migratoria) and cockroach (Periplaneta americana) according to established methods (Gordon et al, , 1992Moskowitz et al, 1994). All buffers contained a mixture of proteinase inhibitors composed of: phenylmethylsulfonyl fluoride (50 g/ml), pepstatin A (1 mM), iodoacetamide (1 mM), and 1 mM 1,10-phenanthroline.…”

Section: Neuronal Membrane Preparationsmentioning

confidence: 99%

“…On the other hand, a possible uniqueness of the insect sodium channels was suggested by the description of two groups of scorpion toxins that modify sodium conductance exclusively in insect neuronal preparations, the excitatory and depressant insect-selective toxins (Pelhate and Zlotkin, 1982;Zlotkin et al, 1985Zlotkin et al, , 1991. These toxins bind selectively to insect sodium channels at two distinct receptor sites (Gordon et al, 1992;Moskowitz et al, 1994) and therefore indicate the existence of unique features in the structure of insect channels, as compared to their mammalian counterparts (Gordon et al, 1984(Gordon et al, , 1992. Thus, a comparative study of mammalian and insect neurotoxin receptor sites on the respective sodium channels may elucidate the structural features involved in the binding and activity of the various neurotoxins and may contribute to the clarification of structure-function relationship in sodium channels.…”

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confidence: 99%

“…2 Sodium channels from various excitable tissues and animal phyla contain a major ␣-subunit of about 240 -280 kDa (Catterall, 1992;Gordon et al, 1988Gordon et al, , 1990, composed of about 2000 amino acids comprising four homologous repeated domains (I-IV), each containing six putative transmembrane ␣-helices (for a review, see Gordon (1990) and Catterall (1992)). Insect sodium channels were shown to resemble their vertebrate counterparts by their primary structure (Loughney et al, 1989), topological organization (Gordon et al, 1992;Moskowitz et al, 1994), and basic biochemical (Gordon et al, 1988(Gordon et al, , 1992Moskowitz et al, 1991Moskowitz et al, , 1994 and pharmacological (Pelhate and Sattelle, 1982;Pelhate and Zlotkin, 1982;Cestele et al, 1995) properties. On the other hand, a possible uniqueness of the insect sodium channels was suggested by the description of two groups of scorpion toxins that modify sodium conductance exclusively in insect neuronal preparations, the excitatory and depressant insect-selective toxins (Pelhate and Zlotkin, 1982;Zlotkin et al, 1985Zlotkin et al, , 1991.…”

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confidence: 99%

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Scorpion Toxins Affecting Sodium Current Inactivation Bind to Distinct Homologous Receptor Sites on Rat Brain and Insect Sodium Channels

Gordon

Martin‐Eauclaire

Cestèle

et al. 1996

Journal of Biological Chemistry

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186

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Sodium channels posses receptor sites for many neurotoxins, of which several groups were shown to inhibit sodium current inactivation. Receptor sites that bind ␣-and ␣-like scorpion toxins are of particular interest since neurotoxin binding at these extracellular regions can affect the inactivation process at intramembranal segments of the channel. We examined, for the first time, the interaction of different scorpion neurotoxins, all affecting sodium current inactivation and toxic to mammals, with ␣-scorpion toxin receptor sites on both mammalian and insect sodium channels. As specific probes for rat and insect sodium channels, we used the radiolabeled ␣-scorpion toxins AaH II and Lqh␣IT, the most active ␣-toxins on mammals and insect, respectively. We demonstrate that the different scorpion toxins may be classified to several groups, according to their in vivo and in vitro activity on mammalian and insect sodium channels. Analysis of competitive binding interaction reveal that each group may occupy a distinct receptor site on sodium channels. The ␣-mammal scorpion toxins and the anti-insect Lqh␣IT bind to homologous but not identical receptor sites on both rat brain and insect sodium channels. Sea anemone toxin ATX II, previously considered to share receptor site 3 with ␣-scorpion toxins, is suggested to bind to a partially overlapping receptor site with both AaH II and Lqh␣IT. Competitive binding interactions with other scorpion toxins suggest the presence of a putative additional receptor site on sodium channels, which may bind a unique group of these scorpion toxins (Bom III and IV), active on both mammals and insects. We suggest the presence of a cluster of receptor sites for scorpion toxins that inhibit sodium current inactivation, which is very similar on insect and rat brain sodium channels, in spite of the structural and pharmacological differences between them. The sea anemone toxin ATX II is also suggested to bind within this cluster.

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“…Significant research has been conducted on both toxins. Zlotkin et al (1991Zlotkin et al ( , 1993 and Moskowitz et al (1994) demonstrated that both toxins are insect-specific.…”

Section: Baculovirus Safetymentioning

confidence: 99%