Differential Translocation of Protein Kinase C e during HeLa Cell Adhesion to a Gelatin Substratum*

The spreading of HeLa cells, following attachment to a collagen or gelatin substratum, requires the activation of protein kinase C (PKC). Membrane-bound PKC was previously shown to be activated during cell attachment and in response to the activation of a series of lipid second messengers turned on by the ligation of b1-inte-grin collagen receptors. HeLa cells express the a, g, e, z, l, and i isozymes of PKC as determined by Western blotting with specific antibodies. Only PKCe redistrib-uted from the cytosol to the membrane during cell ad-hesion. Most of the PKCe in cells that were in suspension was in the cytosolic fraction. During cell attachment to a gelatin matrix, all of the PKCe moved out of the cy-tosol, with most going to the membrane fraction. After the cells became fully spread, PKCe began to reappear i