chylomicron

Definition

Target type: cellularcomponent

A large lipoprotein particle (diameter 75-1200 nm) composed of a central core of triglycerides and cholesterol surrounded by a protein-phospholipid coating. The proteins include one molecule of apolipoprotein B-48 and may include a variety of apolipoproteins, including APOAs, APOCs and APOE. Chylomicrons are found in blood or lymph and carry lipids from the intestines into other body tissues. [GOC:jl, GOC:rl, PMID:10580165]

Chylomicrons are lipoprotein particles that are assembled in the intestinal epithelial cells and are responsible for the transport of dietary lipids, including triglycerides, cholesterol, and phospholipids, from the intestines to the rest of the body. The cellular component of a chylomicron is a complex structure composed of various lipid molecules and proteins that work together to facilitate lipid transport.

**Lipid Components:**

* **Triglycerides:** The primary lipid component of chylomicrons, constituting about 85% of their mass. Triglycerides are composed of three fatty acids esterified to a glycerol molecule. Dietary triglycerides are absorbed in the small intestine and packaged into chylomicrons for transport.
* **Cholesterol:** Chylomicrons also carry cholesterol, both free and esterified forms. Cholesterol is essential for cell membrane structure and hormone synthesis.
* **Phospholipids:** Phospholipids form the outer layer of the chylomicron, creating a hydrophilic surface that allows the particle to interact with the aqueous environment of the bloodstream. Phospholipids are also involved in the binding and transport of specific proteins.

**Protein Components:**

* **Apolipoprotein B-48 (ApoB-48):** This protein is essential for chylomicron assembly and secretion. It serves as a structural backbone for the particle and mediates its interaction with lipoprotein lipase (LPL).
* **Apolipoprotein E (ApoE):** This protein is involved in the uptake of chylomicron remnants by the liver. It also plays a role in cholesterol metabolism.
* **Apolipoprotein C-II (ApoC-II):** This protein acts as a cofactor for lipoprotein lipase (LPL), which hydrolyzes triglycerides in the chylomicron, releasing free fatty acids for delivery to peripheral tissues.
* **Apolipoprotein C-III (ApoC-III):** This protein inhibits the activity of lipoprotein lipase (LPL), thus controlling the rate of triglyceride hydrolysis.

**Structure:**

Chylomicrons are spherical particles with a core of triglycerides surrounded by a monolayer of phospholipids and cholesterol. The protein components are embedded within the phospholipid layer, facing the aqueous environment. This structure allows the chylomicron to remain stable in the bloodstream and transport lipids effectively.'
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Proteins (1)

Compounds (2)