Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.

Synonyms: Protein Modification, Post Translational, Post Translational Amino Acid Modification, Post-Translational Modification, Post-Translational Protein Modifications, Amino Acid Modification, Post Translational, Post Translational Protein Processing, Modification, Post-Translational Protein, Modification, Post-Translational, Modifications, Post-Translational, Modifications, Posttranslational, Post-Translational Protein Modification, Modification, Posttranslational, Protein Modification, Post-Translational, Protein Modifications, Post-Translational, Processing, Posttranslational Protein, Posttranslational Protein Processing, Post-Translational Amino Acid Modification, Processing, Post-Translational Protein, Post Translational Protein Modification, Protein Processing, Post Translational, Post Translational Modifications, Amino Acid Modification, Post-Translational, Posttranslational Amino Acid Modification, Protein Processing, Posttranslational, Post-Translational Protein Processing, Post Translational Modification, Posttranslational Modifications, Post-Translational Modifications, Modifications, Post-Translational Protein, Protein Processing, Post-Translational, Amino Acid Modification, Posttranslational, Posttranslational Modification