In Vitro Reconstitution of a CaMKII Memory Switch by an NMDA Receptor-Derived Peptide |
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Authors: | Hidetoshi Urakubo Miharu Sato Shin Ishii Shinya Kuroda |
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Affiliation: | † Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan;‡ Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo, Japan |
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Abstract: | Ca2+/Calmodulin-dependent protein kinase II (CaMKII) has been shown to play a major role in establishing memories through complex molecular interactions including phosphorylation of multiple synaptic targets. However, it is still controversial whether CaMKII itself serves as a molecular memory because of a lack of direct evidence. Here, we show that a single holoenzyme of CaMKII per se serves as an erasable molecular memory switch. We reconstituted Ca2+/Calmodulin-dependent CaMKII autophosphorylation in the presence of protein phosphatase 1 in vitro, and found that CaMKII phosphorylation shows a switch-like response with history dependence (hysteresis) only in the presence of an N-methyl-D-aspartate receptor-derived peptide. This hysteresis is Ca2+ and protein phosphatase 1 concentration-dependent, indicating that the CaMKII memory switch is not simply caused by an N-methyl-D-aspartate receptor-derived peptide lock of CaMKII in an active conformation. Mutation of a phosphorylation site of the peptide shifted the Ca2+ range of hysteresis. These functions may be crucial for induction and maintenance of long-term synaptic plasticity at hippocampal synapses. |
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