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. Weakly expressed in heart, brain and testis. GPI-anchored form. Belongs to the GDNFR family.