Muscle differentiation in Xenopus laevis is characterized by particular states of vinculin phosphorylation

Vinculin is a 130 kD cytoskeletal protein which is involved in the anchorage of actin microfilaments to the plasma membranes at sites of cell-cell and cell-matrix contacts. In this paper we prove that smooth and cardiac muscles of Xenopus laevis contain a specific isoform of vinculin not present in any other tissue including skeletal muscle and epithelia and we demonstrate that this form of the molecule is characterized by a specific state of phosphorylation. These data are discussed in view of the importance of posttranslational modifications of structural proteins, such as vinculin, in the determination of cellular behaviour during differentiation and development.