<P> Post-translational modifications can occur on the amino acid side chains or at the protein 's C - or N - termini . They can extend the chemical repertoire of the 20 standard amino acids by modifying an existing functional group or introducing a new one such as phosphate . Phosphorylation is a very common mechanism for regulating the activity of enzymes and is the most common post-translational modification . Many eukaryotic proteins also have carbohydrate molecules attached to them in a process called glycosylation , which can promote protein folding and improve stability as well as serving regulatory functions . Attachment of lipid molecules , known as lipidation , often targets a protein or part of a protein attached to the cell membrane . </P>
<P> Post-translational modifications can occur on the amino acid side chains or at the protein 's C - or N - termini . They can extend the chemical repertoire of the 20 standard amino acids by modifying an existing functional group or introducing a new one such as phosphate . Phosphorylation is a very common mechanism for regulating the activity of enzymes and is the most common post-translational modification . Many eukaryotic proteins also have carbohydrate molecules attached to them in a process called glycosylation , which can promote protein folding and improve stability as well as serving regulatory functions . Attachment of lipid molecules , known as lipidation , often targets a protein or part of a protein attached to the cell membrane . </P>
where do post translational modifications occur in the cell
where do post translational modifications occur in the cell
on the amino acid side chains or at the protein 's C - or N - termini
on the amino acid side chains or at the protein 's C - or N - termini