Apolipoprotein A2

Apolipoprotein A2

Apolipoprotein A2 (ApoA2) is a protein that plays a crucial role in lipid metabolism and is a major component of high-density lipoprotein (HDL) in plasma. It is the second most abundant protein in HDL after ApoA1.

Structure

ApoA2 is a dimeric protein, meaning it consists of two identical subunits. Each subunit is composed of 77 amino acids. The protein is encoded by the APOA2 gene located on chromosome 1 in humans. The structure of ApoA2 allows it to interact with lipids and other proteins, contributing to the stability and function of HDL particles.

Function

ApoA2 is involved in the regulation of lipid metabolism. It plays a role in:

• Stabilizing HDL particles: ApoA2 helps maintain the structural integrity of HDL particles, which are responsible for reverse cholesterol transport — the process of transporting cholesterol from peripheral tissues back to the liver for excretion.
• Modulating enzyme activity: ApoA2 influences the activity of enzymes such as LCAT, which is involved in the esterification of cholesterol, and hepatic lipase, which is involved in the metabolism of triglycerides and phospholipids.
• Influencing lipid transfer: ApoA2 affects the transfer of lipids between lipoproteins, impacting the overall lipid profile in the bloodstream.

Clinical Significance

Alterations in ApoA2 levels have been associated with various metabolic disorders:

• Cardiovascular disease: Abnormal levels of ApoA2 have been linked to an increased risk of cardiovascular diseases. The exact role of ApoA2 in atherosclerosis is complex and may depend on its interaction with other lipoproteins and enzymes.
• Metabolic syndrome: ApoA2 levels have been studied in the context of metabolic syndrome, a cluster of conditions that increase the risk of heart disease, stroke, and diabetes.
• Obesity and diabetes: Some studies suggest that ApoA2 may influence body weight regulation and insulin sensitivity, although the mechanisms are not fully understood.

Genetic Variants

Several genetic variants of the APOA2 gene have been identified, some of which are associated with differences in plasma lipid levels and susceptibility to metabolic diseases. For example, the APOA2 -265T>C polymorphism has been studied for its potential impact on dietary response and obesity.

Also see

• Apolipoprotein A1
• High-density lipoprotein
• Lipid metabolism
• Cardiovascular disease
• Metabolic syndrome