Sterol O-Acyltransferase: An enzyme that catalyzes the formation of cholesterol esters by the direct transfer of the fatty acid group from a fatty acyl CoA derivative. This enzyme has been found in the adrenal gland, gonads, liver, intestinal mucosa, and aorta of many mammalian species. EC O-Acyltransferase: An enzyme that catalyzes the acyl group transfer of ACYL COA to 1-acyl-sn-glycerol 3-phosphate to generate 1,2-diacyl-sn-glycerol 3-phosphate. This enzyme has alpha, beta, gamma, delta and epsilon subunits.Sterols: Steroids with a hydroxyl group at C-3 and most of the skeleton of cholestane. Additional carbon atoms may be present in the side chain. (IUPAC Steroid Nomenclature, 1987)Acyltransferases: Enzymes from the transferase class that catalyze the transfer of acyl groups from donor to acceptor, forming either esters or amides. (From Enzyme Nomenclature 1992) EC 2.3.1-Acylglycerophosphocholine O-Acyltransferase: An enzyme localized predominantly within the plasma membrane of lymphocytes. It catalyzes the transfer of long-chain fatty acids, preferentially unsaturated fatty acids, to lysophosphatides with the formation of 1,2-diacylglycero-3-phosphocholine and CoA. EC O-Acyltransferase: An enzyme that catalyses the last step of the TRIACYLGLYCEROL synthesis reaction in which diacylglycerol is covalently joined to LONG-CHAIN ACYL COA to form triglyceride. It was formerly categorized as EC O-Acyltransferase: An enzyme that transfers acyl groups from acyl-CoA to glycerol-3-phosphate to form monoglyceride phosphates. It acts only with CoA derivatives of fatty acids of chain length above C-10. Also forms diglyceride phosphates. EC A 28-amino acid, acylated, orexigenic peptide that is a ligand for GROWTH HORMONE SECRETAGOGUE RECEPTORS. Ghrelin is widely expressed but primarily in the stomach in the adults. Ghrelin acts centrally to stimulate growth hormone secretion and food intake, and peripherally to regulate energy homeostasis. Its large precursor protein, known as appetite-regulating hormone or motilin-related peptide, contains ghrelin and obestatin.Retinol O-Fatty-Acyltransferase: An enzyme that catalyzes the acyl group transfer of acyl COENZYME A to RETINOL to generate COENZYME A and a retinyl ester.Leucomycins: An antibiotic complex produced by Streptomyces kitasatoensis. The complex consists of a mixture of at least eight biologically active components, A1 and A3 to A9. Leucomycins have both antibacterial and antimycoplasmal activities.Acylation: The addition of an organic acid radical into a molecule.Receptors, Ghrelin: Transmembrane proteins that recognize and bind GHRELIN, a potent stimulator of GROWTH HORMONE secretion and food intake in mammals. Ghrelin receptors are found in the pituitary and HYPOTHALAMUS. They belong to the family of G-PROTEIN-COUPLED RECEPTORS.Glycerophospholipids: Derivatives of phosphatidic acid in which the hydrophobic regions are composed of two fatty acids and a polar alcohol is joined to the C-3 position of glycerol through a phosphodiester bond. They are named according to their polar head groups, such as phosphatidylcholine and phosphatidylethanolamine.Acyl Coenzyme A: S-Acyl coenzyme A. Fatty acid coenzyme A derivatives that are involved in the biosynthesis and oxidation of fatty acids as well as in ceramide formation.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Sterol 14-Demethylase: An NADPH-dependent P450 enzyme that plays an essential role in the sterol biosynthetic pathway by catalyzing the demethylation of 14-methyl sterols such as lanosterol. The enzyme acts via the repeated hydroxylation of the 14-methyl group, resulting in its stepwise conversion into an alcohol, an aldehyde and then a carboxylate, which is removed as formic acid. Sterol 14-demethylase is an unusual cytochrome P450 enzyme in that it is found in a broad variety of organisms including ANIMALS; PLANTS; FUNGI; and protozoa.Acetyltransferases: Enzymes catalyzing the transfer of an acetyl group, usually from acetyl coenzyme A, to another compound. EC 2.3.1.Phytosterols: A class of organic compounds known as STEROLS or STEROIDS derived from plants.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Sterol Regulatory Element Binding Protein 1: A sterol regulatory element binding protein that regulates expression of GENES involved in FATTY ACIDS metabolism and LIPOGENESIS. Two major isoforms of the protein exist due to ALTERNATIVE SPLICING.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Ergosterol: A steroid of interest both because its biosynthesis in FUNGI is a target of ANTIFUNGAL AGENTS, notably AZOLES, and because when it is present in SKIN of animals, ULTRAVIOLET RAYS break a bond to result in ERGOCALCIFEROL.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.TriglyceridesSterol Regulatory Element Binding Protein 2: A sterol regulatory element binding protein that regulates GENES involved in CHOLESTEROL synthesis and uptake.StigmasterolMolecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Cholestadienols: Cholestadiene derivatives containing a hydroxy group anywhere in the molecule.Lanosterol: A triterpene that derives from the chair-boat-chair-boat folding of 2,3-oxidosqualene. It is metabolized to CHOLESTEROL and CUCURBITACINS.Desmosterol: An intermediate in the synthesis of cholesterol.Cholestenes: Steroids with methyl groups at C-10 and C-13 and a branched 8-carbon chain at C-17. Members include compounds with any degree of unsaturation; however, CHOLESTADIENES is available for derivatives containing two double bonds.Sterol Regulatory Element Binding Proteins: Sterol regulatory element binding proteins are basic helix-loop-helix leucine zipper transcription factors that bind the sterol regulatory element TCACNCCAC. They are synthesized as precursors that are threaded into the MEMBRANES of the ENDOPLASMIC RETICULUM.Dehydrocholesterols: Cholesterol derivatives having an additional double bond in any position. 24-Dehydrocholesterol is DESMOSTEROL. The other most prevalent dehydrocholesterol is the 7-isomer. This compound is a precursor of cholesterol and of vitamin D3.SqualenePhosphatidylcholine-Sterol O-Acyltransferase: An enzyme secreted from the liver into the plasma of many mammalian species. It catalyzes the esterification of the hydroxyl group of lipoprotein cholesterol by the transfer of a fatty acid from the C-2 position of lecithin. In familial lecithin:cholesterol acyltransferase deficiency disease, the absence of the enzyme results in an excess of unesterified cholesterol in plasma. EC Derivatives of the saturated steroid cholestane with methyl groups at C-18 and C-19 and an iso-octyl side chain at C-17.Cholestanetriol 26-Monooxygenase: An NAPH-dependent cytochrome P450 enzyme that catalyzes the oxidation of the side chain of sterol intermediates such as the 27-hydroxylation of 5-beta-cholestane-3-alpha,7-alpha,12-alpha-triol.Hydroxymethylglutaryl CoA Reductases: Enzymes that catalyze the reversible reduction of alpha-carboxyl group of 3-hydroxy-3-methylglutaryl-coenzyme A to yield MEVALONIC ACID.Hydroxycholesterols: Cholesterol which is substituted by a hydroxy group in any position.Mevalonic Acid