Ligand for the GFR-alpha-3-RET receptor complex but can also activate the GFR-alpha-1-RET receptor complex. Supports the survival of sensory and sympathetic peripheral neurons in culture and also supports the survival of dopaminergic neurons of the ventral mid-brain. Strong attractant of gut hematopoietic cells thus promoting the formation Peyer's patch-like structures, a major component of the gut-associated lymphoid tissue. Homodimer; disulfide-linked. Binds to RET (By similarity). Ubiquitous. Expressed at high levels in peripheral tissues including prostate, placenta, pancreas, heart, kidney, pituitary gland, lung and testis. Expressed at low levels in the brain. Expressed during embryogenesis. High level expression seen in fetal kidney and lung while a low level expression seen in the fetal brain. Belongs to the TGF-beta family. GDNF subfamily.