<prompt> Thyroxine is synthesized from which amino acidArginineLysineMethionineTyrosine  <response>: The thyroid hormones, triiodothyronine T3and thyroxine T4, are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. Iodine is necessary for the production of T3 and T4. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as goitre.Ref: Ganong;s review of medical physiology; 24th edition; page no-341 