When $$Ca^{2+}$$ binds to calmodulin, a large conformational change in calmodulin's EF hands occurs. This conformational change exposes hydrophobic residues on the protein's surface. How might this structural change help to propagate the calcium signal? by allowing calmodulin to bind to other proteins with hydrophobic patches by increasing calmodulin's ability to cross the plasma membrane by increasing calmodulin's affinity for $$Ca^{2+}$$ ions by allowing calmodulin to release the $$Ca^{2+}$$ ions more quickly
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The statement describes that when $$Ca^{2+}$$ binds to calmodulin, a conformational change occurs, exposing hydrophobic residues on calmodulin's surface. This is the key event. Show more…
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Calmodulin is a calcium-binding protein that participates in many signaling events. Calmodulin is activated by calcium via positive cooperative binding to four EF-hand domains. Calcium is normally present at low concentration in the cytoplasm, with local release from ER or mitochondria, or extracellular influx being used to stimulate signaling. If calmodulin had twelve (instead of four) EF-hand domains, and it required all twelve EF-hands to be occupied to become active, how would this change the properties of Ca2+ dependent signaling that occurred via calmodulin? I. Signaling by calmodulin after binding of Ca2+ would begin at a lower concentration of Ca2+. II. Signaling by calmodulin after binding of Ca2+ would begin at a higher concentration of Ca2+. III. The range of activation of calmodulin after binding of Ca2+ would occur over a narrower range of concentration of Ca2+. IV. The range of activation of calmodulin after binding of Ca2+ would occur over a wider range of concentration of Ca2+. Answer options: II only I and IV II and IV I only II and III
Sri K.
What is the role of calmodulin in signaling by $\mathrm{Ca}^{2+}$ ions?
Because calmodulin activates many different effectors (e.g. protein kinases, phosphodiesterases, calcium transport proteins), a calmodulin molecule must have many different binding sites on its surface. Would you agree with this statement? Why or why not?
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