NERVE GROWTH FACTOR

Abstract

Publisher Summary This chapter discusses the structure of nerve growth factor (NGF). The amino acid sequence of mouse NGF exhibited significant structural relatedness with the family of insulins and proinsulins. The sequence of mouse NGF could be aligned with human proinsulin with only five deletions required to yield the maximum homology of 21% identical residue positions. This is indicative of distant, but significant evolutionary relatedness. The majority of the identical residues were seen to be clustered in the segments of NGF, which aligned with the insulin A and B chain regions of the proinsulin sequence, separated by exactly the 35 residues required to accommodate the C activation peptide of proinsulin. Thus, the order of similar regions of NGF is B chain-C peptide-A chain, the same order in which they occur in proinsulin. Because NGF is 118 residues and human proinsulin is 86 residues, 37 residues of the C terminal region of NGF extend beyond the proinsulin molecule. This region is, however, similar to insulin B chain, suggesting a repetitive structure arising from a gene duplication event. It is also noteworthy that three out of the six half cystinyl residues that occur in both proteins are in identical positions, and two of these remain paired in identical fashion in insulin and NGF.