Molecular cloning, expression and tissue distribution of glial-cell-line-derived neurotrophic factor family receptor...

Neurturin and glial-cell-line-derived neurotrophic factor (GDNF) promote the survival and maintenance of different types of neuronal cells and signal through a receptor complex composed of a ligand binding subunit, either GDNF family receptor alpha-1 (GFRalpha-1) or alpha-2 (GFRalpha-2), together with the cRET membrane-bound protein tyrosine kinase. We have cloned GFRalpha-3, a novel receptor belonging to the GFRalpha family, that is 35% identical by amino acid sequence to both GFRalpha-1 and GFRalpha-2. GFRalpha-3 is a protein composed of 400 amino acid residues with three potential N-linked glycosylation sites together with the features characteristic of a glycosyl-phosphatidylinositol-anchored membrane protein. The heterologous expression of a FLAG-tagged GFRalpha-3 in human embryonic kidney cells showed that the protein is bound to the cell surface via a glycosyl-PtdIns anchor and is glycosylated, with different glycoforms migrating on SDS/PAGE with apparent molecular masses ranging over 43-62 kDa. The gene for GFRalpha-3 was mapped to human chromosome 5 in a region (q31.1-q31.3) where several disease loci, growth factor and growth factor receptor genes have been localized. Using northern blot analysis or reverse-transcription PCR, GFRalpha-3 was shown to be expressed within the nervous system predominantly in the cerebellum and the spinal cord while in peripheral tissues GFRalpha-3 was found to be expressed mostly in the colon, small intestine, pancreas, heart, testis and prostate. Using a GFRalpha-3-specific [35S]cRNA[gammaS] probe, in situ hybridization histochemistry experiments confirmed the expression in the cerebellum.