Deciliation induces phosphorylation of a 90-kDa cortical protein in Tetrahymena thermophila

We have used the anti-phosphoprotein antibody MPM-2 to examine changes in phosphorylation of cortical proteins during cilia regeneration in Tetrahymena thermophila. Although numerous cortical proteins are phosphorylated in both nondeciliated and deciliated cells, deciliation induces a dramatic increase in the phosphorylation of a 90-kDa cortical protein. The 90-kDa protein remained phosphorylated during cilia regeneration and then gradually became dephosphorylated. The 90-kDa protein was phosphorylated and dephosphorylated normally in Tetrahymena mutants that assemble short cilia, suggesting that achievement of full length is not the signal that triggers dephosphorylation of the 90-kDa protein. When initiation of cilia assembly is blocked, the 90-kDa protein becomes phosphorylated and remains phosphorylated for an extended period of time, suggesting that initiation of cilia elongation triggers eventual dephosphorylation of the 90-kDa protein, regardless of how long the cilia actually become.