The role of paraxial protocadherin in selective adhesion and cell movements of the mesoderm during Xenopus gastrulation.

Paraxial Protocadherin (PAPC) encodes a transmembrane protein expressed initially in Spemann's organizer and then in paraxial mesoderm. Together with another member of the protocadherin family, Axial Protocadherin (AXPC), it subdivides gastrulating mesoderm into paraxial and axial domains. PAPC has potent homotypic cell adhesion activity in cell dissociation and reaggregation assays. Gain- and loss-of-function microinjection studies indicate that PAPC plays an important role in the convergence and extension movements that drive Xenopus gastrulation. Thus, PAPC is not only an adhesion molecule but also a component of the machinery that drives gastrulation movements in Xenopus. PAPC may provide a link between regulatory genes in Spemann's organizer and the execution of cell behaviors during morphogenesis.