Mouse teratocarcinoma and embryonic development. Two-dimensional protein patterns in nerve differentiation.

The transition in mouse teratocarcinomas of pluripotential stem cells to histogenetically determined ones of the neurogenic cell lineage was analysed at the total cellular protein level by two-dimensional gel electrophoresis. The change in morphology and function was found to be reflected by extensive shifts in the protein synthesis patterns. From a total of about 1000 resolved polypeptides that are synthesized in embryoid bodies of a multidifferentiating teratocarcinoma, about 12% (117 proteins) are not found or only present at a very much reduced level in two teratocarcinoma-derived neuroblastomas. On the other hand, the change in phenotype is accompanied by the de novo or greatly enhanced synthesis of another 69 proteins (about 7%) in the neurogenic tumors. In a screening for differentiation-specific proteins this set was compared with the protein synthesized in neural tissue of maturing brain and muscle tissue of developing limbs at three different postimplantation stages covering the onset of organogenesis. This comparison disclosed that a great portion of the differentiation-related proteins (26 proteins) are synthesized in both brain and muscle and are probably required by a differentiated cell in general like cytostructural proteins. Seventeen polypeptides, however, are synthesized in a cell type specific manner. In particular, 4 proteins that are synthesized in both neurogenic tumors and in brain but not in muscle tissue were tentatively called nerve-specific proteins (NSP) and are the most promising in further analyses of differentiation-specific proteins.