PKC epsilon (protein kinase C-epsilon) is an 87 kDa member of the novel PKC subfamily, AGC Ser/Thr protein kinase family of enzymes. It is a widely-expressed Ca++-insensitive, phospholipid-dependent enzyme that catalyzes the phosphorylation of multiple proteins. Human PKC epsilon is 737 amino acids (aa) in length. It contains two general regions: a non-Ca++-binding plus lipid binding regulatory region (aa 1-99 and 169-292, respectively), and an ATP-binding catalytic domain (aa 408-668). Phosphorylation of PKCe on Thr566, Ser368 and Ser729 activates the enzyme and increases its molecular weight to 92 kDa. One potential splice form shows a 114 aa substitution for aa 118-737. Over aa 580-737, human PKC epsilon is 98% and 99% aa identical to mouse and canine PKC epsilon, respectively.