Emerging role of protein kinase C in energy homeostasis: A brief overview

Figure 1 Domain composition of protein kinase C-β and its regulation at the transcriptional and posttranscriptional levels. A: Membrane-targeting modules (C1 and C2), pleckstrin homology domain, the pseudosubstrate region, the kinase core and the C-terminal tail; B: Schematic representation of promoter structure of protein kinase C-β gene. Approximate locations of known regulatory regions are indicated. ATP: Adenosine-5’-triphosphate; PHLPP: PH domain and leucine rich repeat protein phosphatases; PDK-1: 3-phosphoinositide-dependent protein kinase 1.

Figure 2 Proapoptotic signals, including reactive oxygen species, activate protein kinase C-β, which in turn phosphorylates p66^Shc at serine 36. Phosphorylated p66^Shc translocates to the inner mitochondrial membrane and acts as a redox enzyme to amplify oxidative stress by generating H₂O₂. Increased H₂O₂, in turn, causes opening of the mitochondrial permeability transition pore and apoptosis. Protein kinase C-β (PKCβ) activated by reactive oxygen species further induces p66^Shc phosphorylation. This event in turn perturbs mitochondria structure and function.