Description
Description: GAP-43 (growth associated protein 43 kDa; also known as neuromodulin) is a 24 kDa, neuron growth cone-associated member of the neuromodulin family. Apparently due to its tertiary structure, it runs anomalously at 43 kDa on SDS-polyacrylamide gel. Rat GAP-43 is a 226 amino acid (aa) protein that contains an N-terminal lipid binding motif, an 11 aa IQ domain (IQ:Ile-Gln-X-Ser-etc) (aa 38-48), and a C-terminus with four potential serine phosphorylation sites. The molecule may utilize the IQ domain to bind calmodulin. Protein kinase C-mediated phosphorylation of the Serine at 41 within this site inhibits this interaction. Unphosphorylated, calmodulin-bound GAP-43 is always associated with neurite retraction, while S41 phosphorylated GAP-43 stabilizes actin filaments and promotes growth cone extension