Protein kinase C alpha (PKC α )

Protein kinase C (PKC) is a family of serine-threonine kinases that regulate a broad spectrum of cellular functions. The family is composed of nine genes that express structurally related phospholipid-dependent kinases with distinct means of regulation and tissue distribution. Based on their structures and sensitivities to Ca2+ and diacylglycerol (DAG), they have been classified into conventional PKCs (α, β, and γ), novel PKCs (δ, ε, η, and θ), and atypical PKCs (ζ and λ/ι). Mammalian PKC alpha consists of 672 amino acids and is distributed in all tissues, in contrast to other PKC isotypes whose expression is restricted in the particular tissues. PKC alpha is activated by a variety of stimuli originating from receptor activation, cell contact and physical stresses. Kinase activity of PKC alpha is regulated by phosphorylation of three conserved residues in its kinase domain: the activation-loop site Thr-497, the autophosphorylation site Thr-638, and the hydrophobic C-terminal site Ser-657. In some types of cells, PKC alpha is implicated in cell growth, in contrast, it may play a role in cell cycle arrest and differentiation in other types of cells. The responses are modulated by dynamic interactions with cell-type specific factors.