APOA4 - Apolipoprotein A4 | Elisa - Clia - Antibody - Protein

Background:

Apolipoprotein A4 (APOA4) is a protein (396 AA) involved in lipid metabolism and the regulation of cholesterol levels. APOA4 plays a role in the transport of lipids, particularly triglycerides. It is found in chylomicrons, VLDL (Very Low-Density Lipoprotein), and HDL particles. APOA4 has been identified as a satiety factor, meaning it helps regulate appetite and food intake. Studies suggest that APOA4 may influence satiety signals in the brain, potentially impacting food consumption.There is evidence suggesting that APOA4 has anti-inflammatory properties, which could be beneficial for reducing inflammation in blood vessels and protecting against atherosclerosis. Certain genetic variants of APOA4 and obesity. Variants associated with lower APOA4 levels have been correlated with higher body mass index (BMI) and increased risk of obesity. APOA4 has been studied for its potential role in cardiovascular health. It is associated with HDL particles, which are known for their protective effects against heart disease.

Protein Structure:

• Primary Structure: APOA4 is a single polypeptide chain consisting of 396 amino acids.
• Secondary Structure: The protein contains multiple alpha-helical segments, which are typical of apolipoproteins and crucial for lipid binding.
• Tertiary Structure: The alpha-helices enable APOA4 to interact effectively with lipid surfaces and form stable lipoprotein complexes.
• Quaternary Structure: APOA4 is often found associated with chylomicrons and high-density lipoprotein (HDL) particles in the blood.

Classification and Subtypes:

APOA4 is part of the apolipoprotein family, which includes several classes of proteins involved in lipid transport and metabolism. There are no subtypes of APOA4, but it functions alongside other apolipoproteins, such as APOA1 and APOC3, within lipoprotein particles.

Function and Biological Significance:

• Lipid Transport: APOA4 is involved in the transport of dietary lipids from the intestines to other parts of the body. It helps stabilize chylomicrons, which are large lipoprotein particles that transport dietary triglycerides and cholesterol.
• Cholesterol Metabolism: APOA4 is believed to play a role in the reverse cholesterol transport pathway, facilitating the transfer of cholesterol from peripheral tissues back to the liver for excretion.
• Antioxidant Properties: APOA4 has antioxidant properties that can protect lipoproteins from oxidative damage, which is important in preventing atherosclerosis.
• Satiety Regulation: APOA4 is implicated in the regulation of food intake and energy metabolism. It may have a role in signaling satiety to the brain after fat ingestion.

Interactions:

• Lipid Interactions: APOA4 binds to phospholipids and triglycerides within chylomicrons and HDL particles, contributing to their structure and function.
• Enzymatic Interactions: APOA4 can interact with and activate enzymes such as lecithin-cholesterol acyltransferase (LCAT), which is involved in the esterification of cholesterol on HDL particles.
• Protein Interactions: APOA4 associates with other apolipoproteins, including APOA1 and APOC3, within lipoprotein particles, influencing their composition and metabolic fate.
• Receptor Interactions: APOA4 can interact with lipoprotein receptors on the surface of cells, facilitating the uptake and clearance of lipoproteins from the bloodstream.

Clinical Issues:

• Cardiovascular Disease: Variations in APOA4 levels and genetic polymorphisms in the APOA4 gene have been associated with differences in cardiovascular risk. Elevated levels of APOA4 have been linked to protective effects against atherosclerosis.
• Lipid Disorders: Altered expression of APOA4 can affect lipid metabolism, leading to conditions such as hypertriglyceridemia and dyslipidemia, which are risk factors for cardiovascular disease.
• Metabolic Syndrome: APOA4 levels have been implicated in metabolic syndrome, a cluster of conditions that includes obesity, insulin resistance, and dyslipidemia, increasing the risk of cardiovascular diseases and diabetes.
• Inflammatory Diseases: Due to its antioxidant properties, APOA4 may play a role in modulating inflammation and oxidative stress, which are underlying factors in many chronic diseases.

Summary:

APOA4 is a key apolipoprotein involved in lipid transport and metabolism. It plays a crucial role in the absorption and transport of dietary lipids, cholesterol metabolism, and has antioxidant properties that help protect against atherosclerosis. Variations in APOA4 levels and genetic polymorphisms can influence an individual's risk of cardiovascular disease and other lipid-related disorders. Understanding the functions and interactions of APOA4 is important for developing strategies to manage lipid disorders and reduce cardiovascular risk.