β-NGF Protein, Rat

β-Nerve Growth Factor (β-NGF) is the biologically active subunit of the 7S NGF complex, originally discovered by Rita Levi-Montalcini and Stanley Cohen in the 1950s. In rats, β-NGF is a homodimeric protein composed of two identical 118-amino acid polypeptide chains (approximately 13 kDa per subunit, 26 kDa total), held together by non-covalent interactions. The mature form is generated through proteolytic cleavage of a larger precursor protein (preproNGF).

In the rat nervous system, β-NGF is synthesized primarily in the hippocampus, cortex, and peripheral target tissues innervated by sympathetic and sensory neurons. Its expression is developmentally regulated, with peak levels occurring during critical periods of neuronal differentiation and synaptic formation. The factor exerts its biological effects through binding to two distinct receptor classes: the high-affinity tyrosine kinase receptor TrkA (tropomyosin receptor kinase A), which mediates survival and differentiation signals, and the low-affinity p75 neurotrophin receptor (p75NTR), which can modulate TrkA signaling or induce apoptosis depending on cellular context.