MAMMALIAN NEUROTROPHIN-4 - STRUCTURE, CHROMOSOMAL LOCALIZATION, TISSUE DISTRIBUTION, AND RECEPTOR SPECIFICITY

Nerve growth factor, brain-derived neurotrophic factor, and neurotroph in-3 (NT-3) are the three members of the neurotrophin family known to exist in mammals. Recently, a fourth neurotrophin (designated neurotro phin-4 or NT-4), which shares all of the features found in the mammali an neurotrophins, has been identified in Xenopus and viper. We used se quences specific to the Xenopus/viper NT-4 to isolate a neurotrophin f rom both human and rat genomic DNA that appears to represent the mamma lian counterpart of Xenopus/viper NT-4. Human NT-4 as well as a human NT-4 pseudogene colocalize to chromosome 19 band q13.3. Mammalian NT-4 has many unusual features compared to the previously identified neuro trophins and is less conserved evolutionarily than the other neurotrop hins. However, mammalian NT-4 displays bioactivity and trk receptor sp ecificity similar to that of Xenopus NT-4.