Cholesterol Dissolved
Cholesterol is an essential but intractable sludge-like substance for which mammalian cells must go to great lengths to synthesize, transport, and dispose of. The properties of the cholesterol molecule that render it an attractive component of cellular membranes, namely a rigid tertiary structure and exceptional hydrophobicity, also make it a metabolic bear to deal with. To overcome this mulish behavior, hundreds of proteins are dedicated to man-handling cholesterol into and out of the membrane, and dozens more regulate its expression. Disposal presents a particularly challenging problem as cholesterol is extremely hydrophobic. Sixteen or more hepatic enzymes catalyze a concerted series of reactions that hydroxylate, isomerize, oxidize, reduce, and twist the sterol into a hydrophilic conjugated bile acid that is readily excreted from the liver into the bile and thereafter from the organism.
posted by Selfmaderadio @ 10:24 e paradites
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