Receptor for neurturin. Mediates the NRTN-induced autophosphorylation and activation of the RET receptor. Also able to mediate GDNF signaling through the RET tyrosine kinase receptor. Participates in NRTN-induced 'Ser-727' phosphorylation of STAT3. Interacts with SORL1. Isoform 1 is found in both brain and placenta. Belongs to the GDNFR family.