Biology / Unit 4 Bio 0787 short lesson, about 20 seconds
Small Hydrophobic Ligands: Steroid Hormones
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The idea
A steroid hormone is a small, hydrophobic ligand built on a four-ring skeleton, able to diffuse across the plasma membrane to reach an internal receptor.
In practice
Testosterone and estradiol must bind carrier proteins in blood, since their hydrophobic structure makes them poorly soluble alone.
Where people slip
Do not conclude this steroid is water-soluble — the carrier protein, not its own polarity, keeps it in circulation.
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