Glutamic acid residue ($\mathrm{Glu},\mathrm{E}$)

A glutamic acid residue is an amino acid residue represented by Glu or E in polypeptide sequence notation. GAA and GAG specify glutamic acid residues in the standard genetic code; the ribosome example uses GAA as its third codon. See Elzanowski and Ostell, NCBI: standard genetic code, table 1. The name denotes an incorporated chain position, as distinguished from a free amino acid molecule.