Sciatin: purification and characterization of a myotrophic protein from chicken sciatic nerves

A protein isolated from sciatic nerves of adult chickens promotes the morphological maturation and maintenance of embryonic avian skeletal muscle cells in the absence of innervation and is required for normal myogenesis in vitro. This trophic protein, sciatin, has been purified by ion exchange column chromatography on DEAE-cellulose followed by gel filtration on Sephadex G-100. Sciatin migrated as a single polypeptide chain of molecular weight 84,000 on sodium dodecyl sulfategel electrophoresis. The native molecular weight of sciatin as determined by sedimentation equilibrium centrifugation was 86,400. Amino acid analysis revealed that sciatin is relatively deficient in tryptophan, histidine, glycine, and arginine, but enriched in cysteine, methionine, alanine, and lysine. Carbohydrate determination showed that sciatin in composed of 11% sugar by weight with no detectable N-acetylneuraminic acid residues. Sedimentation velocity centrifugation studies revealed an S20,w0 of 5.11 with a frictional coefficient of 1.31. Sciatin had no detectable protease or acetylcholinesterase activity. The results of the present study provide new biochemical information on a macromolecule with biological activities similar to those expressed by the "maintenance" group of growth factors which includes such proteins as nerve growth factor.