NT-4/5

NT-4/5 (NTF4) is the smallest and least redundant neurotrophin: it binds TrkB as a mature homodimer, sharing this receptor with BDNF but showing a broader tissue distribution and a strikingly milder knockout phenotype, since Ntf4-null mice lose only a small fraction of sensory neurons. NT-4 is expressed in brain, peripheral tissues and adipose, supports survival of motor, sensory and retinal ganglion neurons, and potentiates synaptic transmission. Rare heterozygous NTF4 variants have been reported in primary open-angle glaucoma. Recombinant NT-4/5 is used for TrkB activation assays, neuroprotection studies, retinal ganglion cell cultures and neurite outgrowth experiments.