The present invention discloses purified and isolated nucleic acid sequences encoding polypeptides having a structure substantially similar to that of splicing forms of mammalian GFR.alpha.4 comprising the amino acid sequence (SEQ ID NO:1:)-(SEQ ID NO:6:). The preferred sequences comprise cDNAs having the sequence (SEQ ID NO:7:)-(SEQ ID NO:13:). The present invention is also related to purified and isolated polypeptides comprising the amino acid sequence and or substantially similar splicing forms of mammalian GFRa4. Furthermore, the invention is related to substances capable of specifically recognizing said polypeptides and including both antibodies and receptors. The active compounds of the present invention including cDNAS, polypeptides, binding substances, and antibodies. The invention is useful not only for producing cell-lines and/or transgenic non-human animal but also for diagnosing and treating neuronal disorders or endocrine tumors as well as other related diseases by enabling measurements of GFR.alpha.4-mediated signalling in endocrine cells and neurons.