Aldosterone, in the figure below, is a hormone secreted by the adrenal cortex, and insulin is a peptide secreted by the pancreas. When aldosterone contacts a target cell, it binds to an intracellular receptor and migrates to the nucleus; insulin binds to extracellular receptors on the plasma membrane. What is the MOST likely reason for this difference?

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Quizplus · Accepted Answer

Aldosterone is a steroid hormone, which means it is lipid-soluble and can easily diffuse through the phospholipid bilayer of the plasma membrane. Once inside the cell, it binds to intracellular receptors and migrates to the nucleus to affect gene expression. Insulin, on the other hand, is a peptide hormone and cannot pass through the plasma membrane, so it must bind to extracellular receptors on the membrane surface to initiate a signal cascade inside the cell.

Aldosterone, in the Figure Below, Is a Hormone Secreted by the Adrenal