The ζ Isozyme of Protein Kinase C Binds to Tubulin through the Pseudosubstrate Domain

Abstract

It has been suggested that the protein kinase C zeta (zeta PKC) isoform is involved in mitogenic signaling in Xenopus oocytes and mammalian cells. Thus, the characterization of potential regulatory molecules that bind to zeta PKC is of great interest. We report here the identification by affinity chromatography of tubulin as a zeta PKC-binding protein. Further immunofluorescence and microtubule copolymerization studies are consistent with this interaction. It is suggested that tubulin binds to zeta PKC through its pseudosubstrate domain. Furthermore, results demonstrate that treatment of cells with nocodazole, which disrupts microtubule structures, severely impairs the activity of native zeta PKC, stressing the potential functional relevance of zeta PKC binding to tubulin.