Receptor for persephin. Mediates the GDNF-induced autophosphorylation and activation of the RET receptor. May be important in C-cell development and, in the postnatal development of the adrenal medulla. Interacts with SORL1. Additional isoforms seem to exist. Predominantly expressed in the adult thyroid gland. Low levels also found in fetal adrenal and thyroid glands. Belongs to the GDNFR family.