CaMKII Autophosphorylation Switch

This simulator models the CaMKII holoenzyme — the twelve-subunit kinase parked at the postsynaptic density of an excitatory synapse — as the bistable molecular switch that is widely thought to store synaptic memory. Deliver Ca²⁺ pulse trains at a chosen frequency, influx size, and phosphatase level, and watch the fraction of autophosphorylated (Thr286) subunits climb through a Hill-cooperative, saturating-phosphatase system of ODEs until it snaps between a low state and a self-sustaining high state, exactly the calcium-frequency dependence that separates LTD-inducing low-frequency stimulation from LTP-inducing tetanic bursts. The 3D holoenzyme, rendered as two stacked hexameric rings of instanced subunits, recolors live with each subunit's phosphorylation status, while a ring of AMPA receptors on the postsynaptic membrane grows or shrinks with the resulting synaptic weight.