Purity >95% as determined by SDS-PAGE. Brain-derived neurotrophic factor (BDNF) is a nerve growth factor that binds two receptors, the low-affinity nerve growth factor receptor (LNGFR) and the tropomyosin receptor kinase B (TrkB), to support neuron growth and survival. BDNF expression in the hippocampus is essential for long-term memory storage and learning. Human, mouse, rat, and pig BDNF are cross-reactive.