Lipid Metabolism and Fatty Acid Breakdown

Vocabulary flashcards covering lipid digestion, lipoprotein transport, adipocyte lipolysis, and fatty acid activation and mitochondrial transport.

Triacylglycerol

The principal dietary lipid consisting of three fatty acids esterified to a glycerol backbone, which is hydrolyzed in the small intestine and reassembled inside enterocytes.

Monoacylglycerol

A lipid molecule composed of a single fatty acid attached to glycerol, formed during the intestinal hydrolysis of triacylglycerols.

Chylomicron

The largest lipoprotein particle, composed predominantly of a triacylglycerol core surrounded by phospholipids, cholesterol, and proteins, responsible for distributing dietary fat through the lymph ducts.

APOC2

A surface protein on chylomicrons that associates with lipoprotein lipase in the bloodstream to activate the hydrolysis of triacylglycerols.

Lipoprotein Lipase

An enzyme found in the bloodstream that interacts with APOC2 on chylomicrons to hydrolyze triacylglycerols into free fatty acids.

ApoB-48

The intestinal lipoprotein component of chylomicrons produced from the same gene as ApoB-100, but shortened due to an mRNA premature stop codon.

ApoB-100

The principal full-length protein produced by the liver and incorporated into very low density lipoproteins (VLDL).

Chylomicron Remnant

The cholesterol-enriched particle left behind after most triacylglycerols have been removed from a chylomicron, which travels to and is cleared by the liver.

Lipolysis

The enzymatic pathway triggered by hormones like glucagon in adipose tissue to liberate free fatty acids from stored triacylglycerols for energy production.

Perilipin

A protein coating lipid droplets in adipocytes that, upon phosphorylation by protein kinase A, allows hormone sensitive lipase to bind the droplet surface and releases CGI-58.

CGI-58

A regulatory protein that dissociates from phosphorylated perilipin to bind and activate triacylglycerol lipase.

Triacylglycerol Lipase

An enzyme activated by association with free CGI-58 that catalyzes the conversion of triacylglycerol into a diacylglycerol and a free fatty acid.

Hormone Sensitive Lipase

An enzyme phosphorylated by protein kinase A that binds to the surface of lipid droplets and hydrolyzes diacylglycerols into monoacylglycerols.

Mono Glycerol Lipase

An enzyme that cleaves a monoacylglycerol into a free molecule of glycerol and a free fatty acid.

Serum Albumin

A bloodstream carrier protein that binds hydrophobic free fatty acids to facilitate their transport from adipose tissue to target cells.

Fatty Acyl-CoA Synthetase

An enzyme located on the outer mitochondrial membrane that couples ATP hydrolysis to synthesize fatty acyl adenylate and ultimately fatty acyl-CoA.

Fatty Acid Activation Energy Cost

The expenditure of $2$ equivalents of ATP required to activate a fatty acid of any chain length into a fatty acyl-CoA, due to cleavage into AMP and pyrophosphate ($PP_i$).

Carnitine Shuttle

A transport mechanism that transfers a fatty acid from coenzyme A onto carnitine to form acylcarnitine, enabling its transit across the mitochondrial inner membrane into the matrix.