Cellular Uptake and Intracellular Binding of T3 to Nuclear Thyroid Hormone Receptors

Free T4 and T3 can enter cells by carrier-mediated facilitated diffusion or active transport. After gaining access to the cell interior, T4 may undergo 5'-monodeiodina-tion to yield T3. The T3 thus mixes with T3 entering the cell from the plasma and binds to nuclear TRs. The specific 5'-monodeiodinase enzyme and the level of activity vary from tissue to tissue, as does the contribution of plasma T4 to nuclear TR-bound T3.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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