adp acetylation acylation adenosine diphosphate ribose apoptosis arginine asparagine aspartic acid biochemistry carboxylation cell nucleus cell signaling cholera toxin citrullination cysteine dna repair deamidation deamination desmosine diarrhea digital object identifier disulfide bond eukaryote flavin formylation g protein glutamic acid glutamine glycation glycosylation histone histone code human hydroxylation lysine methylation myristoylation nicotinamide adenine dinucleotide oxidative deamination palmitoylation peptide bond pertussis toxin phosphorylation poly adp ribose polymerase polyglutamylation polyglycylation porphyrin posttranslational modification prenylation primary structure prokaryote proline protein protein biosynthesis proteolysis pyroglutamic acid racemization ribose sumo protein serine telomere threonine toxin tyrosine tyrosine sulfation ubiquitin yeast