The N-methyl-D-aspartic acid (NMDA) subclass of excitatory ionotropic glutamate receptors plays critical roles in neuronal development, plasticity and cell death. The NMDA receptors are thought to be heteromultimers of the core NR1 subunit, one or more regulatory NR2A-D subunits and an additional NR3A subunit. NR3A is a novel, developmentally regulated NMDA receptor subunit. The unique carboxyl intracellular domain of NR3A provides a potential target for interacting with various signal transducing proteins. However, no data are available on protein association with this receptor subunit in the brain. In this study, a yeast two-hybrid system was used to screen for associated proteins that interacted with the NR3A subunit. The upstream 32 amino acids cassette of the NR3A carboxyl intracel...[ Read more ]

The N-methyl-D-aspartic acid (NMDA) subclass of excitatory ionotropic glutamate receptors plays critical roles in neuronal development, plasticity and cell death. The NMDA receptors are thought to be heteromultimers of the core NR1 subunit, one or more regulatory NR2A-D subunits and an additional NR3A subunit. NR3A is a novel, developmentally regulated NMDA receptor subunit. The unique carboxyl intracellular domain of NR3A provides a potential target for interacting with various signal transducing proteins. However, no data are available on protein association with this receptor subunit in the brain. In this study, a yeast two-hybrid system was used to screen for associated proteins that interacted with the NR3A subunit. The upstream 32 amino acids cassette of the NR3A carboxyl intracellular domain was found to bind directly and specifically to the catalytic subunit of the serine/threonine protein phosphatase 2A (PP2A). Results of deletion and co-immunoprecipitation experiments revealed that this interaction could also be observed in mammalian cells. Furthermore, in vivo experiments demonstrated that NR3A formed a stable complex with the holoenzyme in the brain. Intriguingly, inactivation of NMDA receptor channels facilitated the association of PP2A and NR3A. On the other hand, activation of NMDA receptor channels led to the release of PP2A from the NR3A subunit in transfected HEK 293 cells and neurons. This study provides a potential molecular mechanism for the control of NMDA receptor functions by PP2A through serinekhreonine dephosphorylation.