Four different subunits are essential for expressing the synaptic glutamate receptor at neuromuscular junctions of Drosophila.
Three ionotropic glutamate receptor subunits, designated GluRIIA, GluRIIB, and GluRIII, have been identified at neuromuscular junctions of Drosophila. Whereas GluRIIA and GluRIIB are redundant for viability, it was shown recently that GluRIII is essential for both the synaptic localization of GluRIIA and GluRIIB and the viability of Drosophila. Here we identify a fourth and a fifth subunit expressed in the neuromuscular system, which we name GluRIID and GluRIIE. Both new subunits we show to be necessary for survival. Moreover, both GluRIID and GluRIIE are required for the synaptic expression of all other glutamate receptor subunits. All five subunits are interdependent for receptor function, synaptic receptor expression, and viability. This indicates that synaptic glutamate receptors incorporate the GluRIII, GluRIID, and GluRIIE subunit together with either GluRIIA or GluRIIB at the Drosophila neuromuscular junction. At this widely used model synapse, the assembly of four different subunits to form an individual glutamate receptor channel may thus be obligatory. This study opens the way for a further characterization of in vivo glutamate receptor assembly and trafficking using the efficient genetics of Drosophila.
Qin
Gang
G
European Neuroscience Institute Göttingen, Max-Planck-Society, D-37073 Göttingen, Germany.
Schwarz
Tobias
T
Kittel
Robert J
RJ
Schmid
Andreas
A
Rasse
Tobias M
TM
Kappei
Dennis
D
Ponimaskin
Evgeni
E
Heckmann
Manfred
M
Sigrist
Stephan J
SJ
D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western / Q000379:methods; D020169:Caspases / Q000378:metabolism; D003952:Diagnostic Imaging / Q000379:methods; D004330:Drosophila; D029721:Drosophila Proteins / Q000145:classification* / Q000378:metabolism / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D004625:Embryo, Nonmammalian; D015870:Gene Expression / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D007814:Larva; D008564:Membrane Potentials / Q000502:physiology / Q000528:radiation effects; D046228:Microarray Analysis / Q000379:methods; D008967:Molecular Biology / Q000379:methods; D009469:Neuromuscular Junction / Q000502:physiology*; D018408:Patch-Clamp Techniques; D021122:Protein Subunits / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D034622:RNA Interference / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D058468:Receptors, Ionotropic Glutamate / Q000145:classification* / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D017421:Sequence Analysis / Q000379:methods; D009435:Synaptic Transmission / Q000502:physiology*
D029721:Drosophila Proteins; D021122:Protein Subunits; D012333:RNA, Messenger; D058468:Receptors, Ionotropic Glutamate; C000618220:glutamate receptor IIA, Drosophila; C000618221:glutamate receptor IIB, Drosophila; D020169:Caspases; C118731:dronc protein, Drosophila