NUTR 3210 Lecture Notes - Lecture 1: Retinyl Palmitate, Vitamin A Deficiency, Thyroid Hormone Receptor
Document Summary
How does iodide make thyroid hormones: once in the thyroid, iodide reacts with hydrogen peroxide to forma radical (i-), a reactive iodide species. This ia very unique situation, in which there is a chemical production of a hormone that takes pla(cid:272)e o(cid:374) the surfa(cid:272)e of a protei(cid:374), as a (cid:862)post-tra(cid:374)slatio(cid:374)al (cid:373)odifi(cid:272)atio(cid:374)(cid:863) Thyroid hormone signaling: t3 is lipophilic and crosses the plasma membrane. In the nucleus it binds to thr and forms a t3/thr complex and acts as a transcription factor to increase gene expression. Free thr decreases transcription of downstream genes: t3/thr binds to the promoter region of specific regions, gene regulated by t3 signaling (ie gene expression is enhanced by high blood t3 levels) Na+-atpase and ca2+ atpase (maintain ionic gradient for cell signaling) Health consequences: if dietary and blood iodide are too low, the thyroid is still unable to produce sufficient t3 and t4.
