Affinity of an insect Na+-dependent glutamate transporter for plant-derived cyclic substrates

Caveney, Stanley; McLean, Heather; Watson, Ian; Starratt, Alvin N.

doi:10.1016/s0965-1748(96)00033-1

Cited by 6 publications

(15 citation statements)

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“…Several L-2-(carboxycyclopropyl)glycines and methanoproline are present in the young stems (Tables 1 and 2; also Caveney et al, 1996), seeds (Table 3), and fruit pulp (not shown) of Ephedra and may appear in elevated amounts in the stems of greenhouse-grown plants (Tables 1 and 2). Several L-2-(carboxycyclopropyl)glycines and methanoproline are present in the young stems (Tables 1 and 2; also Caveney et al, 1996), seeds (Table 3), and fruit pulp (not shown) of Ephedra and may appear in elevated amounts in the stems of greenhouse-grown plants (Tables 1 and 2).…”

Section: Resultsmentioning

confidence: 99%

“…Total alkaloid content may reach 2.5% dry mass in E. equisetina and E. monosperma stems (Zhang, Tian, and Lou, 1989) and between 1 and 2% in E. gerardiana stems (Grue-Sorensen and Spenser, 1989;Zhang, Tian, and Lou, 1989), E. major ssp. Ephedra distachya and E. sinica are rich in ephedrine (Hegnauer, 1986;Zhang, Tian, and Lou, 1989), whereas European E. distachya appears to be richer in pseudoephedrine (O'Dowd et al, 1998;Caveney and Starratt, 1994) (Table 1). procera (sub E. nebrodensis and E. procera in Hegnauer, 1986;Qazilbach, 1971), and in E. botschantzevii.…”

Section: Resultsmentioning

confidence: 99%

“…Claims that some North American species contain pseudoephedrine (Willaman and Schubert, 1961;Max, 1991) or norpseudoephedrine (Wink, 1998) remain unconfirmed. Several nitrogenous secondary compounds with known neuroactivity, including nonprotein amino acids with cyclopropyl ring structures as well as quinoline-related tryptophan derivatives, have recently been identified in Eurasian species of Ephedra (Caveney and Starratt, 1994;Caveney, 1995, 1996). Several nitrogenous secondary compounds with known neuroactivity, including nonprotein amino acids with cyclopropyl ring structures as well as quinoline-related tryptophan derivatives, have recently been identified in Eurasian species of Ephedra (Caveney and Starratt, 1994;Caveney, 1995, 1996).…”

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confidence: 99%

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New observations on the secondary chemistry of world Ephedra (Ephedraceae)

Caveney

Charlet

Freitag

et al. 2001

American J of Botany

118

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For several millennia, stem extracts of Ephedra (Ephedraceae, Gnetales) have been used as folk medicines in both the Old and New World. Some species were used in treatments of questionable efficacy for venereal disease in North America during the last century. Many Eurasian species produce phenylethylamine alkaloids, mostly ephedrine and pseudoephedrine, that interact with adrenergic receptors in the mammalian sympathetic nervous system. Asian Ephedra have been used recently in the clandestine manufacture of a street drug, methamphetamine. Although ephedrine alkaloids are not detectable in New World species of Ephedra, together with Asian species they contain other nitrogen-containing secondary metabolites with known neuropharmacological activity. Many mesic and particularly xeric species worldwide accumulate substantial amounts of quinoline-2-carboxylic acids, or kynurenates, in their aerial parts. Many species of Ephedra accumulate cyclopropyl amino acid analogues of glutamate and proline in their stems and roots, and particularly in the seed endosperm. Mesic species synthesize substantial amounts of three L-2-(carboxycyclopropyl)glycine stereomers rarely seen in nature. A cyclopropyl analogue of proline with known antimicrobial activity, cis-3,4-methanoproline, is found in large amounts in the stems and seeds of many Ephedra species. The ability to synthesize cyclopropyl amino acids may be an ancestral feature in the taxon. The natural function in the taxon of these three groups of secondary compounds remains to be established.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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New observations on the secondary chemistry of world Ephedra (Ephedraceae)

Caveney

Charlet

Freitag

et al. 2001

American J of Botany

118

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“…The amino acid content of the cells was determined by phenylisothiocyanate derivatization of the cell extract following the Waters Pico-Tag protocol (Millipore) as described by Caveney et al [25]. The incubation procedure was similar to that outlined above, except that six-well plates were used.…”

Section: Ittgvl -Ehsn-lstlekfy Msshgnslflresgqrlgrvgwlqrlqeslqeslqqramentioning

confidence: 99%

“…The region of the chromatographic traces that contains the endogenous aspartate and glutamate peaks also includes the peaks of several cyclic dicarboxylic acids reported to act as potent competitive inhibitors of high-affinity Na+-dependent glutamate transport [25]. Three of these cyclic transport analogues [(2S, 3S, 4R)-2-(carboxycyclopropyl)glycine, L-pyrrolidine-2,4-dicarboxylate, and l-aminocyclobutane-l,3-dicarboxylate] have shorter column retention times than aspartate and glutamate, presumably because of a combination of low-molecular-mass and folded molecular shape [25], and their uptake into TrnEAATl -baculovirus-infected cells can be seen in Fig. 3 (traces 6-8).…”

Section: Uptake Of Transport Substrates By Virally Infected Cellsmentioning

confidence: 99%

Molecular Cloning and Functional Expression of an Insect High‐Affinity Na+‐Dependent Glutamate Transporter

Donly

Richman

Hawkins

et al. 1997

European Journal of Biochemistry

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Excitatory amino acid transporters in the central and peripheral nervous systems of insects are thought to assist in maintaining glutamate concentrations in the resting synapse below the activation threshold of glutamate receptors. We have isolated a cDNA from the caterpillar Trichoplusia ni which encodes a highaffinity Na+-dependent glutamate transporter, designated TrnEAATl . The deduced amino acid sequence shows strong identity with known members of the vertebrate Na+-and K+-dependent amino acid transporter family. Expression of the insect transporter mRNA was predominantly localized in the caterpillar brain. The function of the TrnEAATl protein was analyzed in cultured insect cells using a baculovirus expression system. Cells infected with the recombinant virus were found to exhibit a 50-fold increase in ability to accumulate labeled L-glutamate compared to mock-infected cultures, and this activity was shown to be Na'-dependent. Transport activity was further demonstrated by chromatographic identification of various glutamate analogues accuinulated by infected cells. Various glutamate uptake inhibitors were used to outline the pharmacological properties of the cloned transporter and to compare it with known mammalian transporters. Despite the significant differences between insect and vertebrate physiology, the characteristics of the respective transporters were found to be remarkably similar.Keywords; glutamate transporter; Trichoplusia ni ; insect; cloning ; baculovirus.In recent years, two broad families of high-affinity plasma membrane neurotransmitter transporters have been delineated in mammals [I-31. These molecules are believed to function in terminating the synaptic transmission process for most known neurotransmitters by transporting the transmitter back out of the synaptic space after signalling. This activity is Na+-dependent, being driven by a transmembrane gradient of Na' generated by the plasma membrane Na+/K+-ATPase. The activity of these transporter proteins is crucial for efficient signalling between neurons and their targets, since various neuropathological processes have been associated with abnormalities in transporter function [4].Molecular characterization of various neurotransmitter transporters has revealed that two distinct gene families exist for these proteins. The first is composed of transporters whose activity is dependent on C1-as a cotransported ion. Among the transporters of this type are those for y-aminobutyric acid [5], glycine [6], proline [7], noradrenaline [8], dopamine [9, 101, and 5-hydroxytryptamine [ I I , 121. As a group, the structures of these proteins are typically predicted to have 12 membrane-spanning a-helical domains, including a large extracellular domain (between helices 3 and 4), which characteristically contains potential sites for N-linked glycosylation.A second family of transporters has recently been recognized that is composed primarily of transporters of glutamate [13- [19]. The activities of this group of molecules is functionally distinguished f...

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A Versatile Transport Network for Sequestering and Excreting Plant Glycosides in Leaf Beetles Provides an Evolutionary Flexible Defense Strategy

et al. 2009

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The fourth sentence in the abstract of this paper should read, "Here we address the selectivity of the different transport systems with larvae of Chrysomela populi, an obligate sequestering species, and with larvae of Phaedon cochleariae, producing monoterpene iridoids" and not "nonaterpene iridoids". Also part C of the legend to Figure 6 should read, "structurally unrelated glucosides" not "thioglucosides".

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Affinity of an insect Na+-dependent glutamate transporter for plant-derived cyclic substrates

Cited by 6 publications

References 31 publications

New observations on the secondary chemistry of world Ephedra (Ephedraceae)

New observations on the secondary chemistry of world Ephedra (Ephedraceae)

Molecular Cloning and Functional Expression of an Insect High‐Affinity Na+‐Dependent Glutamate Transporter

A Versatile Transport Network for Sequestering and Excreting Plant Glycosides in Leaf Beetles Provides an Evolutionary Flexible Defense Strategy

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