Distribution of protein kinase M zeta and the complete protein kinase C isoform family in rat brain

Protein kinase C (PKC) is a multigene family of at least ten isoforms, nine of which are expressed in brain (alpha, beta I, beta II, gamma, delta, eps ilon, eta, zeta, iota/lambda). Our previous studies have shown that many of these PKCs participate in synaptic plasticity in the CA1 region of the hip pocampus. Multiple isoforms are transiently activated in the induction phas e of long-term potentiation (LTP). In contrast, a single species, zeta, is persistently activated during the maintenance phase of LTP through the form ation of an independent, constitutively active catalytic domain, protein ki nase M zeta (PKM zeta). In this study, we used immunoblot and immunocytoche mical techniques with isoform-specific antisera to examine the distribution of the complete family of PKC isozymes and PKM zeta in rat brain. Each for m of PKC showed a widespread distribution in the brain with a distinct regi onal pattern of high and low levels of expression. PKM zeta, the predominan t, form of PKM in brain, had high levels in hippocampus, frontal and occipi tal cortex, striatum, and hypothalamus. In the hippocampus, each isoform wa s expressed in a characteristic pattern, with zeta prominent in the CA1 str atum radiatum. These results suggest that the compartmentalization of PKC i soforms in neurons may contribute to their function, with the location of P KM zeta prominent in areas notable for long-term synaptic plasticity. (C) 2 000 Wiley-Liss, Inc.