NH 2 HO -CH -CH-COOH L-tyrosine HO CH2-CH-COOH CH2一CH-cOOH monoiodotyrosine(MIT) diiodotyrosine(DIT) NH 2 HO CH.-CH-COOH Formation of 3,5,3-triodothyronine (T3) thyroxine(Ta) and triiodothyronine(T3) from iodotyrosine HO- CH.-CH-COOH 3, 5, 3, 5, tetraiodothyronine(Ta) ( thyroxine