15453
The data demonstrate the effect of protein density on conformational flexibility and dimensions of the receptors and provide the first structural characterization of functional membrane - embedded AMPARs , thus laying the foundation for correlated structure - function analyses of the predominant mediators of excitatory synaptic signals in the brain .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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