We have cloned two unique forms of glial cell line-derived neurotrophic growth factor transcripts (GDNF-alpha and GDNF-beta) from adult mouse brain. The GDNF-beta form is similar to GDNF-alpha expect for a 78 bp deletion in the ORF. The deduced amino acid sequences of the mouse GDNF-alpha are highly homologous to those of rat and human GDNF. Reverse-transcription PCR from various mouse tissues showed extensive expression of both forms of GDNF. GDNF-alpha is coded by at least two distinct exons. The 3apos-UTR is entirely encoded in a single exon.