* Loading: Analogous to the starting stage, each module loads its specific amino acid onto its PCP-domain.
* Condensation: The C-domain catalyzes the amide bond formation between the thioester group of the growing peptide chain from the previous module with the amino group of the current module. The extended peptide is now attached to the current PCP-domain.
* Condensation-Cyclization: Sometimes the C-domain is replaced by a Cy-domain, which, in addition to the amide bond formation, catalyzes the reaction of the serine, threonine, or cysteine sidechain with the amide-N, thereby forming oxazolidines and thiazolidine, respectively.
* Epimerization: Sometimes an E-domain epimerizes the innermost amino acid of the peptide chain into the D-configuration.
* This cycle is repeated for each elongation module.