You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Which has highest choclestrol content? and explain in detail?
LDL transpos cholesterol from liver to peripheral tissues. The only apoprotein present in LDL is apo B100 (Fig. 12.12). Most of the LDL paicles are derived from VLDL, but a small pa is directly released from liver. The half-life of LDL in blood is about 2 days. Metabolism of LDL and LDL Receptors LDL is taken up by peripheral tissues by receptor-mediated endocytosis (see Fig. 12.13). LDL receptors are present on all cells but most abundant in hepatic cells. LDL receptors are located in specialised regions called clathrin-coated pitsBinding of LDL to the receptor is by apo-B-100 and uptake of cholesterol from LDL is a highly regulated process. When the apo-B-100 binds to the apo-B-100 receptor, the receptor-LDL complex is internalised by endocytosis. The endosome vesicle thus formed fuses with lysosomes. The receptor is recycled and returns to the cell surface. The LDL paicle, along with apoproteins and cholesterol ester is hydrolyzed by lysosomal hydrolases, forming amino acids and free cholesterol. The free receptors can now return to the membrane surface to bind fuher LDL molecules (Fig. 12.13). Approximately 70% of LDL is degraded in the liver, and the rest in extra-hepatic tissues. For their work on LDL receptors, Michael Brown and Joseph Goldstein were awarded Nobel prize in 1985. Function of LDL About 75% of the plasma cholesterol is incorporated into the LDL paicles. LDL transpos cholesterol from liver to the peripheral tissues. The cholesterol thus liberated in the cell has three major fates:It is used for the synthesis of other steroids like steroid hormones.Cholesterol may be incorporated into the membranes.Cholesterol may be esterified to a MUFA by acyl cholesterol acyltransferase (ACAT) for storage. The cellular content of cholesterol regulates fuher endogenous synthesis of cholesterol by regulating HMG CoA reductase.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 153 - 154