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Unformatted text preview: Increased numbers of GLUT-4 receptors transport glucose from blood into the ell where it is rapidly phosphorylated to maintain the glucose concentration gradient. b. At what point do voltage-gated ion channel proteins play a role in this process? Pancreatic beta cells respond to elevated blood glucose by closing potassium channels. This causes a shift in PM transmembrane potential which opens voltage-gated Ca++ channels. A transient rise in cytoplsmic free calcium is required for fusion of insulin containing vesicles with the beta cell PM (exocytosis = secretion of insulin)....
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- Spring '09