Species specificity of an enzyme determined by an erythrocyte nucleus in an interspecific hybrid cell.

In a previous study (Harris & Cook, 1969) it was shown that when a chick erythrocyte nucleus was introduced into the cytoplasm of a mutant mouse cell lacking the enzyme inosinic acid pyrophosphorylase (IMP: pyrophosphate phosphoribosyl transferase, E.C. 2.4.2.8.), synthesis of this enzyme was induced. However, it was not certain whether the enzyme induced in this way was mouse or chick enzyme, or both. Since the precise nature of the genetic defect in the mutant mouse cell is not known, the possibility existed that the introduction of the chick nucleus might stimulate the synthesis of mouse enzyme. The present paper shows that this not so. The enzyme induced by the chick erythrocyte nucleus is chick enzyme.