MDP77: A novel neurite-outgrowth-promoting protein predominantly expressedin chick muscles

A 4.7 kb chick cDNA clone that coded for the novel muscle-derived protein, MDP77, was isolated from a cDNA library of the denervated crus muscles usin g an antibody which inhibited the neurite outgrowth activity. MDP77 consist ed of 676 aa with a calculated molecular mass of 77 k. The deduced amino ac id sequence exhibited an extended coiled coil domain and a leucine zipper m otif. A recombinant protein promoted the neurite-outgrowth from the culture d chick neurons of the spinal cord in a dose-dependent manner. Northern blo tting and in situ hybridization revealed that MDP77 was predominantly expre ssed in the cardiac and the skeletal muscles. In the COS-7 cells transfecte d with the cDNA of the epitope-tagged MDP77, the expressed protein was dete cted in the culture medium, suggesting that the MDP77 was secreted. (C) 200 0 Academic Press.