Terminology

1,25-dihydroxycholecalciferol - A molecule made in kidney from 25-hydroxycholecalciferol. The reaction is stimulated by parathyroid hormone when calcium levels are low. It is the hormonally active form of vitamin D.
25-hydroxycholecalciferol - A molecule which arises from hydroxylation of cholecalciferol at carbon 25.
5-hydroperoxyeicosatetraenoic acid (5-HPETE) - Intermediate in leukotriene biosynthesis produced by action of 5-lipoxygenase on arachidonic acid.
7-dehydrocholesterol - An intermediate in cholesterol biosynthesis that is a precursor of cholecalciferol, vitamin D 3.
Acyl-ACP - Donor of acyl groups in bacterial synthesis of phosphatidic acid from glycerol-3-phosphate. Figure 19.3
Acyl-CoA - Most common form in which acyl groups react in synthesis of acylated lipids. Figure 19.2
Acyltransferases - Enzymes which catalyze transfer of acyl groups in synthesis of lipids.
Adrenocorticotropic Hormone (ACTH) - A hormone whose release is stimulated by corticotropin-releasing hormone, it stimulates the synthesis of the mineralocorticoids and glucocorticoids in the adrenal cortex.
All-trans-retinal - Form of vitamin A released by metarhodopsin II after signal has been sent to activate transducin. Figure 19.27
Androgens - A group of steroid hormones (androstenedione and testosterone) which promote male sexual development and maintain male sex characteristics. Figure 19.24.
Arachidonic Acid - An eicosanoid (all-cis-5,8,11,14-eicosatetraenoic acid) that is a precursor of most of the prostaglandins and thromboxanes.
Aspirin (acetylsalicylic acid) - A non-steroidal anti-inflammatory drug that acts by acetylating PGH synthase to inhibit its cyclooxygenase activity.
Bathorhodopsin - The name of the all-trans-retinal-opsin complex formed by light-induced isomerization of rhodopsin. Figure 19.27.
-Carotene - A precursor of vitamin A in the diet. It is abundant in carrots. Figure 19.25.
Bile Acids - A class of compounds derived from cholesterol with detergent properties. They serve to emulsify dietary lipids in the intestine and promote fat digestion and absorption. Figure 19.23
Bile Salt - Compound formed by combining a bile acid in amide linkage to an amino acid.
Bradykinin - A hormone that can stimulate release of arachidonic acid.
Cholecalciferol (Vitamin D 3) - The most abundant form of vitamin D. It is not required in the diet and arises by ultraviolet light conversion of 7-dehydrocholesterol, an intermediate in cholesterol biosynthesis.
Cholestanol - A fully saturated derivative of cholesterol.
cis-Polyisoprene - A polyprenol that is in natural rubber. Figure 19.28
Corticotropin-releasing Hormone (CRH) - A hormone released from cells in the hypothalamus in response to central nervous system input. It stimulates release of corticotropin or adrenocorticotropic hormone (ACTH).
Diacylglycerol - A molecule containing a glycerol esterified to two acyl groups.
Diethylstilbestrol - A synthetic estrogen, used at one time to promote growth of beef cattle, that is a potential carcinogen.
Diterpene - A term for a terpene derived from geranylgeranyl pyrophosphate Figure 19.28
Eicosanoids - A class of compounds derived from C 20 polyunsaturated fatty acids. They include the prostaglandins, thromboxanes, and leukotrienes.
Enterohepatic Circulation - A pathway taken by bile acids in the body. In it, the bile acids are secreted in the upper small intestine, absorbed in the lower small intestine, and returned to the liver for reuse through the portal blood
Estrogens - A group of steroid hormones (estrone and estradiol), which support female sexual characteristics. Figure 19.24.
Ether Phospholipids - Lipids that contain an alkyl (or alkenyl) group, rather than an acyl group, linked to one of the oxygen atoms of glycerol in a phospholipid.
Exocytosis - A process transferring a compound outside of a cell.
Fatty Acid Hydroperoxides - Oxidized versions of fatty acids created by interaction with superoxides.
Gibberellic Acid - A diterpene that is a plant growth hormone. Figure 19.28
Glucocorticoids - A group of steroid hormones that includes cortisol and corticosterone, which promote gluconeogenesis and, in pharmacological doses, suppress inflammation reactions. Figure 19.24.
Glycerophospholipids (phosphoglycerides) - Lipids based on glycerol that also contain a phosphate. They are found primarily as components of membranes.
Glycosphingolipids - A class of sphingolipids containing carbohydrate(s). It includes cerebrosides and gangliosides. Figure 19.14.
Hydroxyperoxyeicosaenoic Acids Molecules that serve as precursors to the leukotrienes
Ibuprofen - A non-steroidal anti-inflammatory drug that acts by inhibiting the cyclooxygenase activity of a PGH synthase different from the one inhibited by aspirin.
Isoprene - A generalized five-carbon compound that is a building block of the isoprenoids.
Isoprenoids (terpenes) - A class of lipids made by putting together isoprene units. It includes the steroids, bile acids, lipid soluble vitamins, and others.
Juvenile Hormone I - A sesquiterpene that controls metamorphosis in insects. Figure 19.28
LDL Receptor - A cellular receptor that plays an important role in regulating cholesterol levels in the bloodstream.
Leukotriene A 4 - Leukotriene formed from 5-HPETE. Figure 19.32.
Leukotriene B 4 - Leukotriene formed from Leukotriene A 4. Figure 19.32.
Leukotriene C - One of the leukotrienes that is a potent muscle contractant and is thought to be involved in the pathogenesis of asthma through constriction of small airways in the lung.
Leukotriene C 4 - Leukotriene formed from Leukotriene B 4 by addition of glutathione. Figure 19.32
Limonene - A monoterpene responsible for the characteristic odor of lemons. Figure 19.28
Lipid-Soluble Vitamins - A group of four vitamins, A,D,E, and K that are all isoprenoids.
Lung Surfactant - A lipid- and protein-containing substance secreted from lung. By maintaining high surface tension, it prevents collapse of the alveoli when air is expelled. It contains 50%-60% dipalmitoylphosphatidylcholine.
Lycopene - A tetraterpene that is a tomato pigment. Figure 19.28.
Melittin - A protein in bee venom that stimulates arachidonate release.
Metarhodopsin II - Produced from bathorhodopsin by loss of a proton and conformational changes, this is the species that activates transducin to initiate the visual cascade process. Figure 19.27
Mineralocorticoids - A group of steroid hormones (e.g., aldosterone) which regulate ion balance by promoting reabsorption of sodium, chloride, and bicarbonate in the kidney. Figure 19.24
Monoterpene - A term for a terpene derived from geranyl pyrophosphate. Figure 19.28
Myelin Sheath - A multilayered structure that protects and insulates cells of the central nervous system.
Opsin - A protein in the lamellar protein disks of rod cells of the eye that binds to 11-cis-retinal. Figure 19.26, Figure 19.27
Perhydrocyclopentanophenanthrene - Chemical form of the root compound of the steroids. Figure 19.17.
Phosphoinositides - The class of molecules encompassing the different phosphorylated forms of phosphatidylinositol. Some members of the family are important in transmembrane signaling. Figure 19.8.
Plasmalogens - Phospholipids that contain an alkenyl ether at position 1 of glycerol.
Polyprenols (polyisoprenoid alcohols) - A term for an isoprenoid with more than 50 carbons. Figure 19.28.
Progestins - A group of steroid hormones which regulate events during pregnancy and are the precursors to all other steroid hormones.
Respiratory Distress Syndrome - A condition in infants which are unable to either synthesize or secrete lung surfactant.
Retinoids - Compounds derived from retinol.
Rhodopsin - The name of the 11-cis-retinal-opsin complex in the rod cells of the eye. Figure 19.27
Sesquiterpene - A term for a terpene derived from farnesyl pyrophosphate. Figure 19.28
Sphingolipidoses - A group of congenital diseases also known as lipid storage diseases which is characterized by deficiency of one of the degradative enzymes for a sphingolipid, leading to accumulation of the sphingolipid in the lysosomes. Table 19.1
Sphingolipids - Lipids, typically found in nervous tissue in animals, that are based on sphingosine. They are also found in plants and yeast.
Steroid Hormones - A group of hormones (five major classes) derived from cholesterol. Figure 19.24.
Steroids - Lipids which are derived from cholesterol.
Sterol - A class of steroids with an alcohol group. It includes cholesterol.
Tetraterpenes - A term for a terpene derived from four geranyl pyrophosphates. Figure 19.28
Transducin - A G protein that receives the visual signal from metarhodopsin to start the visual cascade.
Triacylglycerol - Another name for a fat or oil. It contains glycerol esterified to three acyl groups.
Triterpene - A term for a terpene derived from two farnesyl pyrophosphates Figure 19.28
TxB 2 - A thromboxane derived by hydrolysis of TxA 2.
Undecaprenol Phosphate - A polyprenol that is a sugar carrier for oligosaccharide synthesis. Figure 19.28
Vitamin A - An isoprenoid alcohol that is also called all-trans-retinol. The aldehyde form (retinal) also plays a key role in vision.
Vitamin D - The only vitamin derived from cholesterol. It acts like a prohormone, because it is converted to a metabolite that acts analogously to a steroid hormone. It is active in regulating calcium and phosphorus metabolism, particularly with respect to synthesis of the inorganic matrix of bone.
Vitamin K - A vitamin originally discovered as a lipid-soluble substance involved in blood coagulation.
Vitamin K 2 (menaquinone) - A form of vitamin K found in animals and bacteria. It has a partly unsaturated side chain. The compound is essential for the carboxylation of glutamate residues iin certain proteins to give -carboxyglutamate. This modification allows a protein to bind calcium. Binding of calcium is an essential event in the blood clotting cascade.