title: Differential regulation of the synthesis of mannosylphosphoryl derivatives of dolichol and retinol in HeLa cells.
abstract: We have shown earlier that in HeLa S3G cells, glucocorticoids stimulate the synthesis of dolichyl phosphorylmannose (Dol-P-Man) with a concomitant increase in the glycosylation of proteins (Ramachandran, C.K., Gray, S.L. and Melnykovych G. (1982) Biochem. J. 208, 47-52). Although controversial, there have been several lines of evidence suggesting that the synthesis of retinyl phosphorylmannose (Ret-P-Man) and Dol-P-Man may be carried out by the same enzyme. We examined this possibility and conclude that in HeLa S3G cells the syntheses of Dol-P-Man and Ret-P-Man are catalyzed by two different enzymes located in the same microenvironment. Our conclusion is based on the following observations: exogenously added dolichyl phosphate and retinyl phosphate did not compete with each other; when the cells were grown in the presence of 1 microM dexamethasone, the microsomal synthesis of Dol-P-Man was stimulated, without affecting the Ret-P-Man synthesis; Arrhenius plots on Ret-P-Man and Dol-P-Man synthesis showed breaks at 22 and 37.7 degrees C.
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004224:Diterpenes; D004287:Dolichol Monophosphate Mannose / Q000096:biosynthesis*; D006367:HeLa Cells / Q000378:metabolism*; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D008364:Mannosyltransferases / Q000378:metabolism; D011103:Polyisoprenyl Phosphate Monosaccharides / Q000096:biosynthesis*; D011105:Polyisoprenyl Phosphate Sugars / Q000096:biosynthesis*; D051381:Rats; D013696:Temperature
chemical_list: D004224:Diterpenes; D008081:Liposomes; D011103:Polyisoprenyl Phosphate Monosaccharides; D011105:Polyisoprenyl Phosphate Sugars; D004287:Dolichol Monophosphate Mannose; C013101:mannosylretinylphosphate; D003907:Dexamethasone; D006903:Hydroxymethylglutaryl CoA Reductases; D008364:Mannosyltransferases