plasma lipoprotein particle assembly

Definition

Target type: biologicalprocess

The non-covalent aggregation and arrangement of proteins and lipids to form a plasma lipoprotein particle. [GOC:BHF, GOC:mah]

Plasma lipoprotein particle assembly is a complex and essential process that enables the transport of lipids, including cholesterol and triglycerides, throughout the body. The assembly of these particles occurs primarily in the liver and small intestine and involves a series of intricate steps.

The initial step involves the synthesis of apolipoproteins, which are protein components that serve as structural components and ligands for lipoprotein receptors. ApoB-100, a large apolipoprotein synthesized in the liver, is a key component of chylomicrons and very-low-density lipoproteins (VLDL).

Next, lipids, mainly triglycerides and cholesterol esters, are packaged into nascent lipoprotein particles. These nascent particles are initially small and lipid-poor, and they acquire additional lipids through a process known as lipidation.

Lipidation occurs as the nascent particles interact with various enzymes and lipid transfer proteins. For example, microsomal triglyceride transfer protein (MTP) facilitates the transfer of triglycerides from the endoplasmic reticulum to the nascent particles.

As the nascent particles accumulate more lipids, they transition into larger, more mature lipoprotein particles.

Chylomicrons, the largest lipoprotein particles, are assembled in the small intestine and primarily transport dietary lipids to peripheral tissues. VLDL particles are assembled in the liver and transport newly synthesized lipids from the liver to the periphery.

As the VLDL particles circulate, they undergo lipolysis, a process where triglycerides are hydrolyzed into free fatty acids and glycerol by lipoprotein lipase (LPL) located on the surface of endothelial cells in capillaries. This process reduces the size of the VLDL particles and generates intermediate-density lipoproteins (IDL).

IDLs are further metabolized, either by being taken up by the liver or by undergoing further lipolysis to form low-density lipoproteins (LDL). LDL particles transport cholesterol to peripheral tissues.

High-density lipoproteins (HDL) are the smallest lipoprotein particles and are primarily synthesized in the liver and small intestine. HDL particles play a crucial role in reverse cholesterol transport, which involves removing excess cholesterol from peripheral tissues and transporting it back to the liver for excretion.

The assembly and metabolism of lipoprotein particles are tightly regulated processes that are influenced by various factors, including diet, genetics, and lifestyle. Dysregulation of lipoprotein metabolism can lead to the accumulation of cholesterol and triglycerides in the blood, contributing to the development of cardiovascular diseases.

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Proteins (1)

Compounds (5)