WEBVTT

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[G-Protein Computer Animation]

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[Description:] This dynamic illustration (animation) of the Signal Transduction idea represents Martin Rodbell's

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revolutionary concept of how cells sense their environment. The small red spheres represent the extracellular signals such as hormones,

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growth factors, cytokines, odorants, taste molecules, ions, light, etc.

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The large green sphere represents the receptor that discriminates and binds extracellular signals.

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The yellow represents the transducer (G-protein), which not only affects the

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binding properties of the receptor to extracellular signals,

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but also is required for activation (or, in some cases, inhibition not represented here)

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of a target protein known as the effector (green) such as adenylyl cyclase.

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This concept is still unchallenged, despite of being more than three decades old. It represents a departure

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from the model proposed by Dr. Earl Sutherland, suggesting that the enzyme

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adenylyl cyclase was both a receptor and an effector for extracellular signals

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(wire framed green bullet, just before the appearance of the three spheres).

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The goal of the animation is to represent the dynamic aspect of the system

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that is critical to the signal transduction process. Although most authors

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consider the transduction process to be unidirectional--the receptor receives the signal,

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and then activates the transducer that, in turn, stimulates or inhibits an effector--Rodbell's view was more complex,

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since he thought that the receptor is influenced also by the transducer which, in turn, is affected by the activity

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of the effector as well (cycling white grains). Thus, this animation faithfully represents Rodbell's thinking

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and was made as a tribute to him.

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[Description provided by Fernando Ribeiro-Neto, April 2000]