Kolesterolsyntese

Kolesterolsyntese, also known as cholesterol biosynthesis, is the metabolic pathway that synthesizes cholesterol. This vital process occurs in most eukaryotic cells, particularly in the liver, intestines, adrenal glands, and reproductive organs. Cholesterol is a crucial component of cell membranes, regulating their fluidity and permeability. It also serves as a precursor for the synthesis of bile acids, steroid hormones, and vitamin D.

The pathway is complex, involving a series of enzymatic reactions that begin with acetyl-CoA. Acetyl-CoA molecules are condensed to form mevalonate, which is then converted through several intermediate steps into squalene. Squalene undergoes cyclization and further modifications to yield cholesterol. Key enzymes involved include HMG-CoA reductase, a rate-limiting enzyme that is a major target for cholesterol-lowering drugs like statins.

Regulation of cholesterol synthesis is tightly controlled to maintain cellular and organismal homeostasis. High intracellular cholesterol levels typically inhibit synthesis, while low levels stimulate it. This regulation is achieved through transcriptional control of key enzymes, as well as post-translational modifications. Disruptions in cholesterol synthesis can lead to various health issues, including hypercholesterolemia and developmental abnormalities. Understanding this pathway is fundamental to comprehending lipid metabolism and its role in health and disease.