Figure 1. Signalling cascades regulating LTD with extension of CaMKII regulating pathways in a Purkinje cell.

A, the Ca²⁺-triggered positive feedback reaction consisting of MAPK, MEK, Raf, PKC, arachidonic acid (AA), and PLA2 (red colour) plays a pivotal role in the LTD induction, which is controlled by the activity of PP-2A (green). AC, adenylyl cyclase; CaN, calcineurin; DAG, diacylglycerol; GC, guanylyl cyclase; pD-32, phospho-DARPP-32; pG-sub, phospho-G-substrate; PLC, phospholipase C; VGCC, voltage-gated Ca²⁺ channel. B, detailed diagrams for molecular reactions of the LTD model with extension of the CaMKII regulating pathways. Kinetics of each numbered reaction are listed in Tables 1–3.