This is what would happen under the myelin sheath. At the end of the

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This is what would happen under the myelin
sheath. At the end of the myelin sheath, the
membrane potential would still be above
threshold, and the action potential would be
regenerated.
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1994 Nobel Prize in Medicine
Alfred G. Gilman
Martin Rodbell
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(1) Resting state
(2) Receptor activates G protein

(3) Alpha sub-unit separates and has action on
amplifier
(4) Alpha sub-unit breaks off of amplifier and
recombines with other sub-units
http//nobelprize.org/medicine/laureates/1994/illp
res/index.html
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A specific example of how a G-protein activates
cAMP

• A first messenger (1) binds to a specific
  receptor (2)
• The transducer (3), a G protein composed of
  alpha-, beta- and gamma subunits is activated
• This stimulates the amplifier (4), adenylate
  cyclase, which produces (5) the second messenger,
  cyclic AMP, from (6) ATP (adenosine triphosphate)
• (7) A cascade of enzymatic reactions alters the
  behavior of the cell and (8) via phosphorylation,
  an ion channel (11) is opened.
• Note ignore (9) and (10)

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