Protein primary structure
![Structure of the protein 1EFN, with focus on the primary structure](/Images/godic/202502/04/Primary_structure4845.png")
![Fig. 1 N-terminal acetylation](/Images/godic/202502/04/N-terminal_acetylation.svg4845.png")
![Fig. 2 Formation of pyroglutamate from an N-terminal glutamine](/Images/godic/202502/04/Formation_of_pyroglutamate.svg4845.png")
![Fig. 3 C-terminal amidation](/Images/godic/202502/04/C-terminal_amidation.svg4845.png")
The primary structure of a peptide or protein is the linear sequence of its amino acid structural units, and partly comprises its overall biomolecular structure. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end.