Identification of multiple PKC isoforms in Swiss 3T3 cells: Differential down‐regulation by phorbol ester

Abstract

The expression of members of the Ca²⁺ and phospholipid‐dependent protein kinase (PKC) family were studied in murine Swiss 3T3 cells. In addition to PKC‐α, the presence of immunoreactive PKC‐δ, ‐ε, and ζ was detected. Treatment with 500 nM 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) led to the down‐regulation of α, δ, and ε isoforms, but not that of ζ. Higher concentrations of TPA similarly had no effect on the level of PKC‐ζ. In contrast to PKC‐α, the membrane localization of PKC‐δ, ‐ε, and ‐ζ was not enhanced by extraction in Ca²⁺‐containing buffers, whereas acute TPA treatment increased membrane association of PKC‐α, ‐δ, and ‐ε but not that of PKC‐ζ.