Protein kinase C gamma mutations in spinocerebellar ataxia 14 increase kinase activity and alter membrane targeting

The protein kinase C gamma (PKCγ) gene is mutated in spinocerebellar ataxia type 14 (SCA14). In this study, we investigated the effects of two SCA14 missense mutations, G118D and C150F, on PKCγ function. We found that these mutations increase the intrinsic activity of PKCγ. Direct visualization of labelled PKCγ in living cells demonstrates that the mutant protein translocates more rapidly to selected regions of the plasma membrane in response to Ca²⁺ influx. These results point to speciic alterations in mutant PKCγ function that could lead to the selective neuronal degeneration of SCA14.