Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, Box 595, New York, New York 10021, USA. m-ptashne@ski.mskcc.org
Yeast growing for a considerable time in glucose 'remember' a previous exposure to galactose, the inducer of its galactose-utilization (GAL) genes. This memory is conveyed by a cytoplasmically transmitted galactokinase working as a signal transducer.