Cryo-EM structures of NPC1L1 reveal mechanisms of cholesterol transport and ezetimibe inhibition.
Level 5 - mechanism / opinion, no new human data
In vitro structural biology study (bench research with no clinical or human subjects data).
PubMed 32596471 · doi:10.1126/sciadv.abb1989
What was done
Researchers used cryo-electron microscopy (cryo-EM) to determine the structures of the intestinal cholesterol transporter NPC1L1 in its apo form and complexed with the inhibitor ezetimibe.
What was found
The apo form shows an open state with the N-terminal domain (NTD) loosely interacting with the rest of NPC1L1, leaving the central cavity accessible. Binding of ezetimibe induces a closed state where the NTD rotates ~60°, forming a continuous tunnel into the plasma membrane. Ezetimibe inhibits transport by occluding this tunnel rather than directly competing for cholesterol binding. No quantitative resolution or affinity metrics were reported in the abstract.
Why it matters
These structures resolve the long-unclear molecular mechanism of ezetimibe, an FDA-approved cholesterol-lowering therapy, providing a framework for rational design of novel transport inhibitors.
Limits
This is an in vitro structural investigation with no functional transport kinetics, in vivo validation, or structural resolution figures reported in the abstract.
Cited by
- supports Zetia (ezetimibe) works by blocking the uptake and absorption of cholesterol.