Tuesday 16 October 2007
Nerve growth factor is a polypeptide involved in the regulation of growth and differentiation of sympathetic and certain sensory neurons.
NGF consists of 3 types of subunits, alpha (NGFA), beta (NGFB) and gamma (NGFC), which specifically interact to form a 7S, 130,000-molecular weight complex.
This complex contains 2 identical 118-amino acid beta-chains, which are solely responsible for nerve growth stimulating activity of NGF.
Human NGF is a 12.5 kDa, nonglycosylated polypeptide 120 aa residues long. Synthesized as a prepropeptide, there is an 18 aa residue signal sequence, a 103 aa residue N-terminal pro-sequence, and a 120 aa residue mature segment.
Human to mouse, there is 90% aa sequence identity in the mature segment. In the mouse, NGF is referred to as beta-NGF, due to the existence of NGF in a 130 kDa (7S) heterotrimeric (abg) complex in submaxillary glands.
Many cells, however, do not synthesize all the components of this 7S complex, and the typical form for NGF is a 25 kDa, non-disulfide linked homodimer. NGF and all other neurotrophins bind to the LNGFR, a member of the TNFRSF.