elizabeth
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Joined: 21 Oct 2000
Posts: 234
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 Posted: 04/09/06 - 10:31 Post subject: |
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As you probably already know, a cell's activity is often regulated by various hormones that we can find in human organism. One of the ways that hormones can affect a cell's activity is by binding to specific hormone receptors. They are activating G-proteins, which then go on to activate other enzymes that direct the cell to function. One such hormone that activates G-proteins is epinephrine. Other name for this important hormone, and maybe widely spread name is Adrenalin. When epinephrine or Adrenalin binds the ß- adrenergic receptor, this activates a G-protein. This one turns activates an enzyme called adenylate cyclase that converts ATP into cAMP. There are many related mechanisms, which caffeine causes on cAMP levels. For example, by inhibiting this adenosine receptor, caffeine removes this check, such that adenylate cyclase activity becomes even more sensitive to hormone binding, which is connected with pulse rate. That is why, by preventing various enzymes from binding to molecules containing adenine, caffeine can yield the same physiological effects as epinephrine, though less intense.
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