GluA1 signal peptide determines the spatial assembly of heteromeric AMPA receptors.
AMPA-type glutamate receptors (AMPARs) mediate fast excitatory neurotransmission and predominantly assemble as heterotetramers in the brain. Recently, the crystal structures of homotetrameric GluA2 demonstrated that AMPARs are assembled with two pairs of conformationally distinct subunits, in a dimer of dimers formation. However, the structure of heteromeric AMPARs remains unclear. Guided by the GluA2 structure, we performed cysteine mutant cross-linking experiments in full-length GluA1/A2, aiming to draw the heteromeric AMPAR architecture. We found that the amino-terminal domains determine the first level of heterodimer formation. When the dimers further assemble into tetramers, GluA1 and GluA2 subunits have preferred positions, possessing a 1-2-1-2 spatial assembly. By swapping the critical sequences, we surprisingly found that the spatial assembly pattern is controlled by the excisable signal peptides. Replacements with an unrelated GluK2 signal peptide demonstrated that GluA1 signal peptide plays a critical role in determining the spatial priority. Our study thus uncovers the spatial assembly of an important type of glutamate receptors in the brain and reveals a novel function of signal peptides.
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China;
Xue-Yan
0000-0002-8797-2915
XY
He
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China;
Yan-Jun
YJ
Li
Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158;
Chakrapani
C
Kalyanaraman
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China; Department of Anesthesiology, Zhongda Hospital, Medical School, Southeast University, Nanjing 210009, China;
Li-Li
LL
Qiu
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China;
Chen
C
Chen
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China;
Qi
Q
Xiao
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China; Department of Intensive Care Medicine, Zhongda Hospital, Medical School, Southeast University, Nanjing 210009, China;
Wen-Xue
WX
Liu
Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang 050017, China.
Wei
W
Zhang
Department of Anesthesiology, Zhongda Hospital, Medical School, Southeast University, Nanjing 210009, China;
Jian-Jun
JJ
Yang
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China;
Guiquan
G
Chen
Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158;
Matthew P
MP
Jacobson
State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210061 China; yunshi@nju.edu.cn.
Yun Stone
YS
Shi
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D019281:Dimerization; D006801:Humans; D011487:Protein Conformation; D021382:Protein Sorting Signals / Q000235:genetics; D051381:Rats; D018091:Receptors, AMPA / Q000737:chemistry* / Q000235:genetics; D009435:Synaptic Transmission
D021382:Protein Sorting Signals; D018091:Receptors, AMPA; C104722:glutamate receptor ionotropic, AMPA 2
AMPA receptors; signal peptide; spatial assembly; stoichiometry