PKMζ, LTP maintenance, and long-term memory storage

Although the signaling pathways regulating learning and the initial consolidation of memory have been extensively studied, the molecular mechanism maintaining memory storage has been unknown. Work on the maintenance of long-term potentiation (LTP), however, has identified a simple molecular mechanism involving gene expression of a constitutively active form of protein kinase C (PKC), protein kinase Mzeta (PKMζ), which sustains synaptic potentiation over time. Recent studies have shown that PKMζ also maintains the storage of memory for days to weeks. This chapter reviews the current state of knowledge on PKMζ, focusing on its discovery and the elucidation of its unique structure as an autonomously active form of PKC, its function in LTP maintenance, and its role in normal memory storage and disorders of memory.