Isozymic forms of protein kinase C in regenerating rat liver.

The expression of multiple forms of protein kinase C (PK-C) was studied in regenerating rat liver using hydroxyapatite column chromatography. Two forms of the enzyme were found in the cytosolic as well as membrane fraction of livers from partially hepatectomized rats. The kinetic variation in the activation of these two liver isozymes by fatty acids, phosphatidylserine and diacylglycerol was similar to that reported for the PK-C subspecies from rat brain, designated types II and III. Intracellular redistribution of PK-C caused by phorbol 12-myristate 13-acetate (PMA) was concentration-dependent and was due to translocation of isozyme III, because type II was insensitive to 5 x 10(-8) M PMA. The activity ratio of the two isozymes in either the particulate or cytosolic fraction was the same at 22 h as compared to 4 h after partial hepatectomy.