lipidcarrying

Lipid carrying refers to the biological processes by which lipids are transported within an organism. Lipids are hydrophobic and require carriers to move through aqueous environments such as blood plasma. In vertebrates, the main carriers are lipoproteins in the bloodstream, albumin for free fatty acids, and specialized lipoproteins formed after meal digestion known as chylomicrons. Cells also use intracellular lipid-binding proteins to shuttle lipids within the cytoplasm.

Circulatory transport describes how dietary and endogenous lipids are moved through the body. Dietary fats are emulsified and absorbed as chylomicrons by enterocytes; chylomicrons enter the lymphatic system before reaching the bloodstream. The liver secretes very-low-density lipoprotein (VLDL) to deliver triglycerides to tissues, where lipoprotein lipase hydrolyzes triglycerides, yielding remnants taken up by the liver. High-density lipoprotein (HDL) participates in reverse cholesterol transport, collecting cholesterol from peripheral tissues for delivery to the liver. Low-density lipoprotein (LDL) and HDL differ in their cargo and receptor interactions, with LDL delivering cholesterol to tissues and HDL facilitating cholesterol homeostasis via receptor-mediated uptake.

Molecular composition notes that lipoproteins are complexes of triglycerides, cholesterol esters, phospholipids, and apolipoproteins. Apolipoproteins, such as ApoB-48, ApoB-100, ApoA-I, and ApoE, provide structural integrity and mediate receptor binding and enzyme activation, guiding the fate of each particle.

Intracellular transport covers fatty acids bound to albumin in plasma and intracellular carriers such as fatty acid–binding proteins that direct lipids to membranes, mitochondria, and other organelles. Cytosolic lipid droplets store triglycerides for energy and lipid supply.

Clinical relevance includes disorders of lipid transport, such as hyperlipoproteinemias and abetalipoproteinemia, as well as therapies that modulate lipoprotein metabolism to manage cardiovascular risk.