Involved in the planar cell polarity pathway that controls convergent extension during gastrulation and neural tube closure. Convergent extension is a complex morphogenetic process during which cells elongate, move mediolaterally, and intercalate between neighboring cells, leading to convergence toward the mediolateral axis and extension along the anteroposterior axis. Necessary for nuclear localization of REST. May serve as nuclear receptor. Interacts with REST. A smaller amount is detected in the cytosol. Expressed at highest levels in placenta and at lower levels in lung, liver, kidney and pancreas. Expressed in thalamus, hippocampus, cerebral cortex, and cerebellum (in neurons rather than glia). The disease is caused by variants affecting the gene represented in this entry. Disease susceptibility is associated with variants affecting the gene represented in this entry. Belongs to the prickle / espinas / testin family.