ANIMAL PHYSIOLOGY
CHEMICAL SIGNALS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The ligand would bind, and the signaling pathway would proceed through transduction to cellular response.
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The ligand would bind, but the signaling pathway would not proceed through the transduction step.
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The ligand would bind and the signaling pathway would proceed through the transduction step, but would not produce a cellular response.
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Detailed explanation-1: -If phosphorylation (of ATP or GTP) did not occur, what would happen? The ligand would bind, and the signaling pathway would proceed through transduction to cellular response.
Detailed explanation-2: -The GTP bound form is an active conformation that turns on the transmission of signals, and the hydrolysis of bound GTP to bound ODP is required to shift the conformation to an inactive form, i.e. to tum off the signal transduction.
Detailed explanation-3: -Gated ion channels form a pore through the plasma membrane that opens when the signaling molecule binds. The open pore then allows ions to flow into or out of the cell. Ion channel-linked receptors bind a ligand and open a channel through the membrane that allows specific ions to pass through.
Detailed explanation-4: -When a ligand binds an ion channel receptor, a channel through the plasma membrane opens that allows specific ions to pass through. This process requires a specialized membrane-spanning region of the receptor.
Detailed explanation-5: -As a result of the ligand binding to its site on the G-protein-linked receptor, the G-protein changes conformation and GTP replaces the GDP on the alpha subunit. The alpha subunit can repeatedly dissociate from and associate with the remainder of the G-protein as long as the ligand is bound to the receptor.