Wang et al. knock down PKCι/λ or PKMζ in the dorsal hippocampus and find specific deficits in LTP and hippocampus-dependent LTM expression and maintenance. Sequential increases in PKCι/λ and PKMζ are detected during LTP or LTM, indicating that PKCι/λ and PKMζ have distinct functions in LTP and memory (Cell Reports 2016; cover story, recommended by Faculty of 1000).