Biochemistry · Topic
Chylomicron !
Chylomicrons are the largest lipoproteins: they carry dietary fat from the gut, through the lymph, to the tissues.
Updated 2026-11-01
Key facts
- Enterocytes build them after a meal; their structural protein is ApoB-48.
- They are the largest and least dense; about 85–90% of their mass is triglyceride.
- They enter the blood through the lymph and thoracic duct, not the portal vein.
- LPL empties them within minutes; the remnants go to the liver via ApoE.
In detail
- Formation: MTP loads lipid onto ApoB-48 in the enterocyte ER.
- Maturation: in blood they receive ApoC-II and ApoE from HDL.
- Hydrolysis: capillary LPL frees fatty acids for muscle (fuel) and adipose tissue (storage).
- Remnant: it returns ApoC-II and the liver takes it up via ApoE.
- After a 12-hour fast no chylomicrons normally remain in plasma.
Clinical notes
- LPL or ApoC-II deficiency piles up chylomicrons: milky plasma, eruptive xanthomas and pancreatitis.
- Without MTP they cannot form: abetalipoproteinaemia, with malabsorption of fat and fat-soluble vitamins.
- Dietary vitamins A, D, E and K travel in chylomicrons.
Related conditions
- Familial chylomicronemia syndrome (lipoprotein lipase deficiency)
- Abetalipoproteinemia (Bassen–Kornzweig syndrome)
- Acute pancreatitis
Related
- Lipoprotein metabolism
- Lipoprotein lipase (LPL)
- Apolipoprotein B (ApoB-100 and ApoB-48)
- Apolipoprotein E (ApoE)
- VLDL (very-low-density lipoprotein)
- HDL (high-density lipoprotein)
Test yourself
Think of the answer, then tap the question to see it.
Which structural apolipoprotein does the chylomicron carry?
ApoB-48.
What does milky serum after a 12-hour fast suggest?
Persistent chylomicrons, as in LPL or ApoC-II deficiency.
Why does abetalipoproteinaemia cause vitamin E deficiency?
Without chylomicrons fat-soluble vitamins are not absorbed or carried.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Chylomicron assembly (R-HSA-8963888) (Reactome, 2026); Familial lipoprotein lipase deficiency: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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Representative model, for educational purposes only.