Three types of cDNA clone of the protein kinase C family termed delta, epsilon and zeta were newly identified by molecular cloning and sequence analysis. These members have a common structure that is closely related to, but clearly different from the other four known members of the family which have alpha-, beta I-, beta II- and gamma-sequences, although the zeta-cDNA available at present does not contain a complete reading frame for a protein kinase C molecule. The diverse heterogeneity of the enzyme seems to be an important factor in determining the mode of response of many tissues and cell types to a variety of external stimuli.