This schematic shows the strategy Zhang et al. used for making glycosylated myoglobin protein in E. coli. A plasmid encoding the myoglobin with the amber codon, TAG, was transformed into E.coli (top).

Normally synthesis of myoglobin is halted at the stop codon, but when a mutant tRNA that recognizes TAG, a mutant synthetase that loads that tRNA with a glycosylated amino acid, and that amino acid are added, the glycosylated myoglobin protein is produced inside the E. coli (bottom).

Illustration by Kevin Fung.