It does not only determine the shape of cells but is the basis for all intracellular and whole-cell movements, too. It consists of three independent systems, the microtubuli system , the microfilament system and the system of intermediate filaments. Coated vesicles develop during endocytosis. Their membrane stems either from the plasmalemma or from intracellular membranes. Microfilaments and microtubuli have a great deal in common.
Polymerisation is reversible and is balanced by depolymerisation.
On the protein level could no homologies of actin and tubuline be detected. The recognition will be discussed elsewhere. And about the signal transduction to elements of the cytosceleton is so far not much known.