<Li> Special cases <Ul> <Li> Cysteine </Li> <Li> Selenocysteine </Li> <Li> Glycine </Li> <Li> Proline </Li> </Ul> </Li> <Ul> <Li> Cysteine </Li> <Li> Selenocysteine </Li> <Li> Glycine </Li> <Li> Proline </Li> </Ul> <Li> Hydrophobic side chains <Ul> <Li> Alanine </Li> <Li> Valine </Li> <Li> Isoleucine </Li> <Li> Leucine </Li> <Li> Methionine </Li> <Li> Phenylalanine </Li> <Li> Tyrosine </Li> <Li> Tryptophan </Li> </Ul> </Li> <Ul> <Li> Alanine </Li> <Li> Valine </Li> <Li> Isoleucine </Li> <Li> Leucine </Li> <Li> Methionine </Li> <Li> Phenylalanine </Li> <Li> Tyrosine </Li> <Li> Tryptophan </Li> </Ul>

Where does the initial stage of protein breakdown occur