Cloning of a cDNA that encodes an invertebrate glutamate receptor subunit

Abstract

A full-length eDNA which encodes a putative glutamate receptor polypeptide was isolated from the pond snail Lymnaea stagnalis, using a short stretch of exonic sequence and two variants of the polymerase chain reaction. In this first comparison of invertebrate and vertebrate glutamate receptor sequences, the mature molluscan polypeptide, which comprises 898 amino acids and has a predicted M~ of 100 913, displays between 37% and 46% amino-acid identity to the rat ionotropie glutamate receptor subunits, GIuRI to GIuR6.

pT305-CaMKII stabilizes a learning-induced increase in AMPA receptors for ongoing memory consolidation after classical conditioning

“…The cloning and sequence analysis of a GluA-like gene from the pond snail Lymnaea stagnalis by Hutton et al 54 predicted a mature peptide with 898 amino acids and an N-terminal signal peptide 55 with 19 amino acids. The predicted size of this GluA1-like protein was about ~101 kDa; further hydrophobic analysis of this sequence clearly revealed the presence of three strongly hydrophobic regions which correspond to the TM1, TM3 and TM4 transmembrane regions of vertebrate ionotropic glutamate receptor subunits 54,56 . This mature peptide, which was subsequently named Lym-eGluR1 57 , shares substantial amino acid sequence homology with mammalian AMPA-selective subunits, and more than with other selective subunits.…”

GABAA- and AMPA-like receptors modulate the activity of an identified neuron within the central pattern generator of the pond snail Lymnaea stagnalis

“…In this regard, it is noticeable that the Lymnaea GluR subunit is unable to produce detectable ion currents when expressed in Xenopus oocytes. It has been proposed that it requires at least one additional subunit to form a fully functional receptor complex in vivo (Hutton et al 1991). The central role played by AMPA-sensitive GluRs in the onset of aerial breathing in L. stagnalis concurs with the results obtained in vertebrates (Rekling and Feldman 1998).…”

“…The following pieces of evidence indicate a central role for Glu in the rhythmical excitation of RPeD1 following activation of AMPA-selective GluRs: (1) superfusion of isolated CRG with a desensitizing concentration of Glu rapidly inhibits the spontaneously occurring, patterned respiratory activity; (2) AMPA is the only agonist to completely desensitize the rhythmical firing, with lower (if none) efficacy displayed by kainite and NMDA-selective GluRs; (3) AMPA induces electrical firing in silent RPeD1 neurons; and (4) a mature polypeptide, with a 37-46% amino acid identity to the rat AMPA subunits GluR1-6, has been cloned from Lymnaea CNS (Hutton et al 1991), albeit its pharmacological profile is different to the Glu response on RPeD1 (Nesic et al 1996). In this regard, it is noticeable that the Lymnaea GluR subunit is unable to produce detectable ion currents when expressed in Xenopus oocytes.…”

“…We therefore hypothesized that non-NMDA receptors were involved in the initiation of the respiratory rhythm. The two ionotropic non-NMDA GluRs that have been cloned in L. stagnalis display a selective sensitivity to the glutamatergic agonists, AMPA and kainate, respectively (Hutton et al 1991;Stühmer et al 1996). Therefore, the electrophysiological effects of such agonists on the whole respiratory circuit were investigated and compared with those exerted by Glu.…”

“…Glutamate (Glu) is a putative candidate as the neurotransmitter initiating the regular bursting activity which drives aerial respiration. This hypothesis stems from the observation that Glu depolarizes RPeD1 (Nesic et al 1996) and that ionotropic glutamate receptor (GluR) polypeptides with high homology sequence to a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-sensitive GluR subunits (GluR1-4) and kainate-selective GluR subunits (GluR5-7) have been cloned from the Lymnaea nervous system (Hutton et al 1991;Stühmer et al 1996). NMDA-like receptors were first described in the CNS of Lymnaea by Moroz et al (1993) and effects on RPeD1 were first described by Mishmast-Nehi and Winlow (1995).…”