title: Oviduct dolichyl phosphate phosphatase: estrogen effects and a possible biosynthetic role.
abstract: Estrogen-induced chick oviduct differentiation is accompanied by an increased capacity for protein glycosylation. A portion of this increase has been attributed to increased levels of dolichyl phosphate (Dol-P). Hormone withdrawal leads to an apparent decrease in Dol-P. Dol-P metabolism in the oviduct has been studied, and one of the enzymes having a direct effect on Dol-P, Dol-P phosphatase is herein described. Dol-P phosphatase has a pH optimum of 6.0, does not require a metal ion, and is inhibited by Mn2+ at concentrations greater than 5 mM. Inhibitor studies indicate that Dol-P hydrolysis is inhibited by polyprenyl phosphates having both saturated and unsaturated alpha-isoprene residues, but not by the corresponding alcohols. The enzyme is also inhibited by phosphatidic acid unless 2 mM Mn2+ is included in the incubations. Under these conditions Dol-P hydrolysis is only slightly inhibited (less than 10%), but phosphatidate inhibition is totally eliminated. Oviduct membranes also possess phosphatidate phosphatase, but this enzyme is distinct from Dol-P phosphatase based on thermolability, metal ion sensitivity, and sulfhydryl reagent sensitivity. Studies of enzyme activity in response to estrogen treatment reveal that both Dol-P phosphatase and phosphatidate phosphatase have maximal specific activity early in the differentiation process (peaking after 3 days of treatment), and low specific activity in fully differentiated oviducts, including laying hen oviduct. Hormone withdrawal elicits a small increase in specific activity of both phosphatases. The hormone effects suggest that Dol-P phosphatase may be a biosynthetic enzyme.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002645:Chickens; D004054:Diethylstilbestrol / Q000494:pharmacology*; D004288:Dolichol Phosphates / Q000378:metabolism; D004355:Drug Stability; D005260:Female; D006358:Hot Temperature; D006868:Hydrolysis; D008670:Metals / Q000494:pharmacology; D010057:Oviducts / Q000187:drug effects / Q000201:enzymology*; D010711:Phosphatidate Phosphatase / Q000378:metabolism; D010712:Phosphatidic Acids / Q000378:metabolism / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D004288:Dolichol Phosphates; D008670:Metals; D010712:Phosphatidic Acids; D013439:Sulfhydryl Reagents; C028306:dolichol monophosphate; D004054:Diethylstilbestrol; D010744:Phosphoric Monoester Hydrolases; D010711:Phosphatidate Phosphatase; C020088:dolichyl-phosphatase