Comparison of the polypeptides of normal (mec+) cells and derived metabolic cooperation-defective (mec-) variants of Syrian hamster cells.

The polypeptide profiles of a polyoma virus-transformed Syrian hamster cell line (PyY/HGPRT^?/ dCK^?/TK^?) and a derivative which is defective in metabolic cooperation when TdR is supplied (mec^?) have been compared. At least eleven polypeptide differences exist between the mec⁺ and mec^? cell lines. When the mec^? cells are cultured with 1 mM dibutyryl cyclic AMP (db-cAMP) and 1 mM theophylline in the medium, they become phenotypically mec⁺. Coincidentally the polyacrylamide gel electrophoresis pattern of six of the polypeptides, which were altered in the mec^? cell line, changes back to resemble the mec⁺ polypeptide profile. It has been shown [1, 2] that mec^? cells differ in morphology from mec⁺ cells and that treatment of mec^? cells with the two drugs causes their morphology to revert to that of mec⁺ cells. Thus gross morphology of the mec^? cells is correlated both with their capability for metabolic cooperation and with the appearance or disappearance of six polypeptides. These six polypeptides (mol. wts 28 000, 27 500, 15 500, 15 000, 13 500 and 13 000) are therefore candidates for involvement in the mechanism of metabolic cooperation.