title: Inositol lipid binding and membrane localization of isolated pleckstrin homology (PH) domains. Studies on the PH domains of phospholipase C delta 1 and p130.
abstract: The relationship between the ability of isolated pleckstrin homology (PH) domains to bind inositol lipids or soluble inositol phosphates in vitro and to localize to cellular membranes in live cells was examined by comparing the PH domains of phospholipase Cdelta(1) (PLCdelta(1)) and the recently cloned PLC-like protein p130 fused to the green fluorescent protein (GFP). The prominent membrane localization of PLCdelta(1)PH-GFP was paralleled with high affinity binding to inositol 1,4,5-trisphosphate (InsP(3)) as well as to phosphatidylinositol 4,5-bisphosphate-containing lipid vesicles or nitrocellulose membrane strips. In contrast, no membrane localization was observed with p130PH-GFP despite its InsP(3) and phosphatidylinositol 4,5-bisphosphate-binding properties being comparable with those of PLCdelta(1)PH-GFP. The N-terminal ligand binding domain of the type I InsP(3) receptor also failed to localize to the plasma membrane despite its 5-fold higher affinity to InsP(3) than the PH domains. By using a chimeric approach and cassette mutagenesis, the C-terminal alpha-helix and the short loop between the beta6-beta7 sheets of the PLCdelta(1)PH domain, in addition to its InsP(3)-binding region, were identified as critical components for membrane localization in intact cells. These data indicate that binding to the inositol phosphate head group is necessary but may not be sufficient for membrane localization of the PLCdelta(1)PH-GFP fusion protein, and motifs located within the C-terminal half of the PH domain provide auxiliary contacts with additional membrane components.
authors.affiliation: Endocrinology and Reproduction Research Branch, NICHD/National Institutes of Health, 49 Convent Drive, Bldg. 49, Bethesda, MD 20892, USA.
authors.forename: Péter
authors.initials: P
authors.lastname: Várnai
authors.forename: Xuena
authors.initials: X
authors.lastname: Lin
authors.forename: Sang Bong
authors.initials: SB
authors.lastname: Lee
authors.forename: Galina
authors.initials: G
authors.lastname: Tuymetova
authors.forename: Tzvetanka
authors.initials: T
authors.lastname: Bondeva
authors.forename: Andras
authors.initials: A
authors.lastname: Spät
authors.forename: Sue Goo
authors.initials: SG
authors.lastname: Rhee
authors.forename: György
authors.initials: G
authors.lastname: Hajnóczky
authors.forename: Tamas
authors.initials: T
authors.lastname: Balla
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000737:chemistry; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004735:Energy Transfer; D004926:Escherichia coli / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D020128:Inhibitory Concentration 50; D007294:Inositol / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry*; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D054803:Phospholipase C delta; D010750:Phosphoproteins / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D002118:Calcium; D004247:DNA; D049452:Green Fluorescent Proteins; D007294:Inositol; D007527:Isoenzymes; D008055:Lipids; D008164:Luminescent Proteins; D019869:Phosphatidylinositol 3-Kinases; D054803:Phospholipase C delta; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D010738:Type C Phospholipases; C039077:platelet protein P47; C518024:PLCD1 protein, human