title: A low molecular weight substance purified from human placenta inhibits cAMP-dependent protein kinase and activates protein kinase C.
abstract: We have purified from human placenta a low molecular mass substance that inhibits cAMP-dependent protein kinase and activates protein kinase C. This protein kinase regulator was purified in three steps: (1) homogenizing placentas in chloroform/methanol and extracting the regulator into water; (2) eluting a strong anion exchange high performance liquid chromatography (HPLC) column with a quaternary gradient; and (3) eluting a reversed-phase HPLC column with a binary gradient. The regulator was found to be highly purified by HPLC, thin-layer chromatography (TLC) and laser desorption ionization mass spectrometry with a molecular mass of 703 Daltons by the latter procedure. The physical and biochemical properties of this protein kinase regulator suggest that it is a phospholipid but it did not co-elute by HPLC or by TLC with any of the known phospholipid activators of protein kinase C.
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla 92093-0652, USA.
authors.forename: N
authors.initials: N
authors.lastname: Talwar
authors.forename: R B
authors.initials: RB
authors.lastname: Pilz
authors.forename: Z
authors.initials: Z
authors.lastname: Yu
authors.forename: A
authors.initials: A
authors.lastname: Burlingame
authors.forename: G R
authors.initials: GR
authors.lastname: Boss
mesh_terms: D001685:Biological Factors / Q000302:isolation & purification / Q000494:pharmacology*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D002855:Chromatography, Thin Layer; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D010743:Phospholipids / Q000494:pharmacology*; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D011493:Protein Kinase C / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001685:Biological Factors; D010743:Phospholipids; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C