Protein kinase Cζ and n in murine epidermis TPA induces down‐regulation of PKCn but not PKCζ

Abstract

Murine epidermis contains PKCζ and n as evidenced by the application or specific antisera. PKCζ predominates in the cytosol and PKCn in the particulate fraction. PKCζ is shown to be present also in other murine tissues, with large amounts found in lung. Whereas epidermal PKCn is completely down-regulated by treatment or mouse skin with TPA or bryostatin 1 for 18 h. PKCζ is neither translocated by treatment with TPA for 20 min, nor down-regulated by treatment with TPA or bryostatin 1 for 18 h. PKCζ is activated by phosphatidyl serine alone and does neither respond to Ca²⁺ nor to TPA. It is inhibited by staurosporine with an IC₅₀ of 16 nM, which is within the same range or other PKC isoenzymes. The sensitivity of PKCζ towards the staurosporine derivative K252a is similar to that or PKCα,β,γ but much higher than that of PKCδ and ε.