(A) In dendritic spines, both NMDA receptor activation (1) and L-VGCC activation (2) contribute to mobilizing the entire pool of REs to fuse with the PM in response to synaptic stimulation.
(B) In dendritic shafts, synaptic NMDA receptor activation (1) drives the initial mobilization of REs to the PM and fusion pore opening, while subsequent L-VGCC activation (2) promotes full RE collapse and fusion into the PM, which delivers integral membrane proteins to the dendritic PM.