Trophic factor for dopamine neurons. Prevents the 6-hydroxydopamine (6-OHDA)-induced degeneration of dopaminergic neurons. When administered after 6-OHDA-lesioning, restores the dopaminergic function and prevents the degeneration of dopaminergic neurons in substantia nigra (By similarity). Expressed at high levels in the heart, skeletal muscle, testis and brain (at protein level). In the brain, detected in the cerebral cortex neurons through layers II to VI. In the hippocampus, detected in the CA1 to CA3 pyramidal regions and in the granule and polymorph layers of dentate gyrus. Weak expression in the striatum. In substantia nigra, detected in solitary cells that did not express tyrosine hydroxylase, a marker for dopaminergic neurons. Relatively high expression in the Purkinje cells of the cerebellum and in regions of the brain stem, including the locus coeruleus. At postnatal stage P1 and P10, expressed in the brain, including the hippocampus, thalamus, striatum and substantia nigra. Highest levels in the hippocampus and thalamus. Belongs to the ARMET family.