Chick muscle-derived protein 62: a novel neurite outgrowth promoting protein.

A 3.2 kb chick cDNA clone that coded for a novel muscle-derived protein, MDP62, was isolated from a cDNA library of the denervated crus muscles using an antibody which inhibited the neurite (dendritic and axonal processes) outgrowth activity. MDP62 consisted of 539 aa with a calculated molecular mass of 62 k. The predicted protein sequence was hydrophilic and exhibited an extended coiled-coil domain and a leucine zipper motif. A recombinant protein promoted the neurite outgrowth from the cultured chick neurons of the telencephalon in a dose dependent manner. Northern blotting revealed that MDP77 was ubiquitously expressed. In the transfected COS-7 cells with the cDNA of the epitope-tagged MDP62, the expressed protein was detected in the culture medium, suggesting that the MDP62 might be secreted.