How do amino acids like hydroxylysine and thyroxine, which are not among the 20 amino acids inserted into amino acid chains, get into proteins?

Question

Quizplus · Accepted Answer

Hydroxylysine and thyroxine are not one of the 20 standard amino acids, but they can be formed from the modification of the side chains of some of the standard amino acids after their incorporation into the polypeptide chain. For example, hydroxylysine is formed from the post-translational modification of lysine, and thyroxine is derived from the amino acid tyrosine.

How Do Amino Acids Like Hydroxylysine and Thyroxine, Which Are