Immunochemical characterization and cellular distribution of protein kinase C isozymes in the bovine corpus luteum.

Research was conducted to determine the nature of the isoforms of protein kinase C (PKC) present in the bovine (Bos taurus) corpus luteum (CL) and their subcellular distribution. Western blot analysis was performed using isozyme-specific polyclonal antibodies and revealed that the bovine corpus luteum contains the alpha and epsilon isozymes of PKC, but not the beta, gamma, delta or zeta isozymes. Subcellular fractionation demonstrated that the alpha and epsilon isozymes of PKC were present in both the cytosolic and plasma membrane fractions. Densitometric measurements of Western blots of the subcellular luteal PKC fractions indicated that PKC alpha was found predominantly in the cytosolic fraction, whereas the majority of PKC epsilon was associated with the plasma membrane.