title: Immunocytochemical techniques reveal multiple, distinct cellular pools of PtdIns4P and PtdIns(4,5)P(2).
abstract: PtdIns4P is the major precursor for the synthesis of the multifunctional plasma membrane lipid, PtdIns(4,5)P(2). Yet PtdIns4P also functions as a regulatory lipid in its own right, particularly at the Golgi apparatus. In the present study we define specific conditions that enable preservation of several organellar membranes for the immunocytochemical detection of PtdIns4P. We report distinct pools of this lipid in both Golgi and plasma membranes, which are synthesized by different PI4K (phosphatidylinositol 4-kinase) activities, and also the presence of PtdIns4P in cytoplasmic vesicles, which are not readily identifiable as PI4K containing trafficking intermediates. In addition, we present evidence that the majority of PtdIns4P resides in the plasma membrane, where it is metabolically distinct from the steady-state plasma membrane pool of PtdIns(4,5)P(2).
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge, UK. gruh2@cam.ac.uk
authors.forename: Gerald R V
authors.initials: GR
authors.lastname: Hammond
authors.forename: Giampietro
authors.initials: G
authors.lastname: Schiavo
authors.forename: Robin F
authors.initials: RF
authors.lastname: Irvine
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D000918:Antibody Specificity / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002645:Chickens; D003902:Detergents / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000201:enzymology; D007150:Immunohistochemistry; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013194:Staining and Labeling; D013696:Temperature
chemical_list: D000906:Antibodies; D015415:Biomarkers; D003902:Detergents; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D047428:Protein Kinase Inhibitors; C037178:phosphatidylinositol 4-phosphate; D004815:Epidermal Growth Factor; D019870:1-Phosphatidylinositol 4-Kinase; D010749:Phosphoprotein Phosphatases