Neurotrophin-4 (NT-4) like BDNF, is a neurotrophic factor that signals predominantly through the TrkB receptor tyrosine kinase. It is also known as NT4, NT5, NTF4, and NT-4/5. Differentiation, survival, and function of neurons in vertebrates are controlled by multiple, target-derived neurotrophic factors. The best characterized mammalian neurotrophic factors are 4 structurally related 13- to 14-kD basic proteins known as neurotrophinsBerkemeier et al. (1992) identified a cluster of genes on human chromosome 19 that includes neurotrophin-5 (NT5) and 3 pseudogenes, designated NTF6A, NTF6B, and NTF6G. The NTF5 and NTF6 gene loci were mapped to chromosome 19 by Southern analysis of somatic cell hybrid panels. In the mouse, the Ntf5 gene was assigned to chromosome 7.