title: Glycerolipid synthesis in rat adipose tissue. II. Properties and distribution of phosphatidate phosphatase.
abstract: The properties and subcellular distribution of phosphatidate phosphatase (EC 3.1.3.4) from adipose tissue have been investigated. The enzyme was assayed using both aqueous phosphatidate and membrane-bound phosphatidate as substrates. When measured with aqueous substrate, activity was detected in the mitochondria, the microsomes, and the soluble fraction. Mg(2+) at low concentration stimulated the phosphatidate phosphatase from soluble and microsomal fractions but had no effect on the mitochondrial phosphatidate phosphatase. At higher concentration Mg(2+) was inhibitory. In the presence of Mg(2+), the phosphatidate phosphatase from soluble and microsomal fractions was active against membrane-bound phosphatidate. No activity was demonstrated with membrane-bound substrate in the absence of Mg(2+). Mitochondria did not contain activity toward the membrane-bound substrate. The rate of utilization of aqueous phosphatidate was always higher than that of membrane-bound substrate. These results indicate that there are at least two different phosphatidate phosphatases in adipose tissue.
mesh_terms: D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D002247:Carbon Isotopes; D002462:Cell Membrane; D002855:Chromatography, Thin Layer; D003600:Cytosol / Q000201:enzymology; D004492:Edetic Acid / Q000494:pharmacology; D004822:Epididymis; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008861:Microsomes / Q000201:enzymology; D008928:Mitochondria / Q000201:enzymology; D010743:Phospholipids; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D051381:Rats; D012995:Solubility; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D002247:Carbon Isotopes; D010743:Phospholipids; D004492:Edetic Acid; D010744:Phosphoric Monoester Hydrolases; D008274:Magnesium