Isoform specificity of activators and inhibitors of protein kinase C gamma and delta

Expression of certain mammalian protein kinase C (PKC) isoforms inhibits the proliferation of Schizosaccharomyces pombe (Goode et al., Mel. Biol, Cell 5 (1994) 907-920). We have taken advantage of this fact to determine the in vivo isoform preference of a number of PKC inhibitors, using a microtitre plate assay which allows rapid screening, This in vivo model has revealed previously unreported preferences; calphostin C is a more efficient inhibitor of the novel PKC delta than chelerythrine chloride whereas the efficiencies are reversed for inhibition of the classical PKC gamma. We have also shown that the anti-leukaemic agent bryostatin 1 inhibits or activates in vivo in an isoform-specific manner, (C) 1997 Federation of European Biochemical Societies.