Publications

• Mixed function oxidases in sterol metabolism. Source of reducing equivalents.

  Brady D.R., Crowder R.D., Hayes W.J.

  Either NADH or NADPH can serve as a cofactor for oxidative demethylation of [30,31-14C]4,4-dimethyl-5 alpha-cholest-7-en-3 beta-ol and oxidative deformylation of 4-hydroxy[14C]methylene-5 alpha-cholest-7-en-3-one. This report suggests that the cofactors interact with these two oxidase systems diff ... >> More

  Either NADH or NADPH can serve as a cofactor for oxidative demethylation of [30,31-14C]4,4-dimethyl-5 alpha-cholest-7-en-3 beta-ol and oxidative deformylation of 4-hydroxy[14C]methylene-5 alpha-cholest-7-en-3-one. This report suggests that the cofactors interact with these two oxidase systems differently depending upon whether the reduced cofactor arises intra- or extramicrosomally. Marked differences in oxidative activity are observed depending on whether NADPH is generated in the microsomes or is added as an exogenous cofactor. Thus, the concentration of added NADPH required to yield maximal rates of sterol oxidation is 500 muM or greater. Nearly equivalent rates of sterol oxidation are obtained from NADPH generated in the microsomes where the NADPH concentration is no greater than 0.454 muM. Similar results are observed with NADH. In this case, NADH is generated in the microsomes from added NAD+ by microsomal reactions. The rate of sterol oxidation when NADH is generated from added NAD+ is nearly the same as that obtained from added NADH; although the concentration of NADH generated from NAD+ is 0.403 muM, the concentration of added NADH is 100 muM, and Km for added NADH is 1.7 muM. << Less

  J Biol Chem 255:10624-10629(1980) [PubMed] [EuropePMC]

  This publication is cited by 7 other entries.

• NSDHL, an enzyme involved in cholesterol biosynthesis, traffics through the Golgi and accumulates on ER membranes and on the surface of lipid droplets.

  Caldas H., Herman G.E.

  NSDHL, for NAD(P)H steroid dehydrogenase-like, encodes a sterol dehydrogenase or decarboxylase involved in the sequential removal of two C-4 methyl groups in post-squalene cholesterol biosynthesis. Mutations in this gene are associated with human CHILD syndrome (congenital hemidysplasia with ichth ... >> More

  NSDHL, for NAD(P)H steroid dehydrogenase-like, encodes a sterol dehydrogenase or decarboxylase involved in the sequential removal of two C-4 methyl groups in post-squalene cholesterol biosynthesis. Mutations in this gene are associated with human CHILD syndrome (congenital hemidysplasia with ichthyosiform nevus and limb defects), an X-linked, male lethal disorder, as well as the mouse mutations bare patches and striated. In the present study, we have investigated the subcellular localization of tagged proteins encoded by wild-type and selected mutant murine Nsdhl alleles using confocal microscopy. In addition to an ER localization commonly found for enzymes of post-squalene cholesterol biosynthesis, we have identified a novel association of NSDHL with lipid droplets, which are endoplasmic reticulum (ER)-derived cytoplasmic structures that contain a neutral lipid core. We further demonstrate that trafficking through the Golgi is necessary for ER membrane localization of the protein and propose a model for the association of NSDHL with lipid droplets. The dual localization of NSDHL within ER membranes and on the surface of lipid droplets may provide another mechanism for regulation of the levels and sites of accumulation of intracellular cholesterol. << Less

  Hum. Mol. Genet. 12:2981-2991(2003) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Partial purification of a microsomal sterol 4 -carboxylic acid decarboxylase.

  Rahimtula A.D., Gaylor J.L.

  J Biol Chem 247:9-15(1972) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Characterization of the Saccharomyces cerevisiae ERG26 gene encoding the C-3 sterol dehydrogenase (C-4 decarboxylase) involved in sterol biosynthesis.

  Gachotte D., Barbuch R., Gaylor J., Nickel E., Bard M.

  All but two genes involved in the ergosterol biosynthetic pathway in Saccharomyces cerevisiae have been cloned, and their corresponding mutants have been described. The remaining genes encode the C-3 sterol dehydrogenase (C-4 decarboxylase) and the 3-keto sterol reductase and in concert with the C ... >> More

  All but two genes involved in the ergosterol biosynthetic pathway in Saccharomyces cerevisiae have been cloned, and their corresponding mutants have been described. The remaining genes encode the C-3 sterol dehydrogenase (C-4 decarboxylase) and the 3-keto sterol reductase and in concert with the C-4 sterol methyloxidase (ERG25) catalyze the sequential removal of the two methyl groups at the sterol C-4 position. The protein sequence of the Nocardia sp NAD(P)-dependent cholesterol dehydrogenase responsible for the conversion of cholesterol to its 3-keto derivative shows 30% similarity to a 329-aa Saccharomyces ORF, YGL001c, suggesting a possible role of YGL001c in sterol decarboxylation. The disruption of the YGL001c ORF was made in a diploid strain, and the segregants were plated onto sterol supplemented media under anaerobic growth conditions. Segregants containing the YGL001c disruption were not viable after transfer to fresh, sterol-supplemented media. However, one segregant was able to grow, and genetic analysis indicated that it contained a hem3 mutation. The YGL001c (ERG26) disruption also was viable in a hem 1Delta strain grown in the presence of ergosterol. Introduction of the erg26 mutation into an erg1 (squalene epoxidase) strain also was viable in ergosterol-supplemented media. We demonstrated that erg26 mutants grown on various sterol and heme-supplemented media accumulate nonesterified carboxylic acid sterols such as 4beta, 14alpha-dimethyl-4alpha-carboxy-cholesta-8,24-dien-3be ta-ol and 4beta-methyl-4alpha-carboxy-cholesta-8,24-dien-3beta-o l, the predicted substrates for the C-3 sterol dehydrogenase. Accumulation of these sterol molecules in a heme-competent erg26 strain results in an accumulation of toxic-oxygenated sterol intermediates that prevent growth, even in the presence of exogenously added sterol. << Less

  Proc. Natl. Acad. Sci. U.S.A. 95:13794-13799(1998) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.