Phosphatidylinositol transfer proteins: requirements in phospholipase C signaling and in regulated exocytosis

Cockcroft, Shamshad

doi:10.1016/s0014-5793(97)00414-6

Cited by 19 publications

(16 citation statements)

References 31 publications

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“…It is possible that in vivo other PtdIns 4-kinase-or PtdIns4P-binding proteins, such as PtdInsP kinase, PtdIns4P phosphatase, or PtdIns4P lipid transfer protein, profilin (Drøbak et al, 1994), actin depolymerizing factor (Gungabissoon et al, 1998), and/or dynamins (Kim et al, 2001) could also selectively increase AtPI4K␣1 activity by relieving feedback inhibition. The need for the involvement of a lipid transfer protein to pass PtdIn4P from enzyme to enzyme has been proposed by Cockcroft (1997Cockcroft ( , 1998. That the ␤-isoform is product stimulated may suggest that PtdIns4P recruits an activating protein; for instance, Arf1, which has been shown to activate the ␤ isoform of PtdIns 4-kinase (Audhya et al, 2000;Jones et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Differential Regulation of Two Arabidopsis Type III Phosphatidylinositol 4-Kinase Isoforms. A Regulatory Role for the Pleckstrin Homology Domain

2003

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Here, we compare the regulation and localization of the Arabidopsis type III phosphatidylinositol (PtdIns) 4-kinases, AtPI4K␣1 and AtPI4K␤1, in Spodoptera frugiperda (Sf9) insect cells. We also explore the role of the pleckstrin homology (PH) domain in regulating AtPI4K␣1. Recombinant kinase activity was found to be differentially sensitive to PtdIns-4-phosphate (PtdIns4P), the product of the reaction. The specific activity of AtPI4K␣1 was inhibited 70% by 0.5 mm PtdIns4P. The effect of PtdIns4P was not simply due to charge because AtPI4K␣1 activity was stimulated approximately 50% by equal concentrations of the other negatively charged lipids, PtdIns3P, phosphatidic acid, and phosphatidyl-serine. Furthermore, inhibition of AtPI4K␣1 by PtdIns4P could be alleviated by adding recombinant AtPI4K␣1 PH domain, which selectively binds to PtdIns4P (Stevenson et al., 1998). In contrast, the specific activity of AtPI4K␤1, which does not have a PH domain, was stimulated 2-fold by PtdIns4P but not other negatively charged lipids. Visualization of green fluorescent protein fusion proteins in insect cells revealed that AtPI4K␣1 was associated primarily with membranes in the perinuclear region, whereas AtPI4K␤1 was in the cytosol and associated with small vesicles throughout the cytoplasm. Expression of AtPI4K␣1 without the PH domain in the insect cells compromised PtdIns 4-kinase activity and caused mislocalization of the kinase. The green fluorescent protein-PH domain alone was associated with intracellular membranes and the plasma membrane. In vitro, the PH domain appeared to be necessary for association of AtPI4K␣1 with fine actin filaments. These studies support the idea that the Arabidopsis type III PtdIns 4-kinases are responsible for distinct phosphoinositide pools.The negatively charged polyphosphorylated inositol lipids, phosphatidylinositol (PtdIns)-4-phosphate (PtdIns4P) and PtdIns(4,5)P 2 , are important biochemical cues for regulating vesicle formation and trafficking, cytoskeletal dynamics, membrane protein binding, and enzyme activity (Munnik et al., 1998;Stevenson et al., 2000;Wang, 2001;De Matteis et al., 2002) in addition to being precursors of the second messenger inositol(1,4,5)trisphosphate (Berridge and Irvine, 1989). Because of the multiple roles of the phosphoinositides (PIs) in cellular metabolism, regulation of PI biosynthesis is integral to both the response to and recovery from external stimuli. PtdIns 4-kinase, the enzyme that synthesizes PtdIns4P, is the first committed step in PtdIns(4,5)P 2 biosynthesis; therefore, regulation of PtdIns 4-kinase activity and/or its subcellular distribution could affect not only PtdIns4P biosynthesis but also the biosynthesis and distribution of PtdIns(4,5)P 2 .In plants, PtdIns 4-kinase activity has been reported to be associated with many cellular compartments such as the plasma membrane (Sommarin, 1988;Gross et al., 1992; Cho et al., 1993), cytosol (Okpodu et al., 1995), cytoskeleton (Tan and Boss, 1992;Xu et al., 1992), and the nucleus (Hendrix et al., 1989;...

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Section: Discussionmentioning

confidence: 99%

Differential Regulation of Two Arabidopsis Type III Phosphatidylinositol 4-Kinase Isoforms. A Regulatory Role for the Pleckstrin Homology Domain

2003

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“…It has been proposed that the formation of these vesicles involves the local conversion of PI into metabolites that cause the remodelling of the phospholipid bilayer in the vicinity of a coated bud (28). PI-TP␣ would play a role in this conversion by delivering PI as a substrate to PI kinases (31). However, whether PI-TP␣ fulfills a role in the phosphorylation of PI in intact cells has not been confirmed.…”

Section: Discussionmentioning

confidence: 99%

The Protein Kinase C-dependent Phosphorylation of Serine 166 Is Controlled by the Phospholipid Species Bound to the Phosphatidylinositol Transfer Protein α

Tiel

Westerman

Paasman

et al. 2000

Journal of Biological Chemistry

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The charge isomers of bovine brain PI-TP␣ (i.e. PI-TP␣I containing a phosphatidylinositol (PI) molecule and PI-TP␣II containing a phosphatidylcholine (PC) molecule) were phosphorylated in vitro by rat brain protein kinase C (PKC) at different rates. From the doublereciprocal plot, it was estimated that the V max values for PI-TP␣I and II were 2.0 and 6.0 nmol/min, respectively; the K m values for both charge isomers were about equal, i.e. 0.7 M. Phosphorylation of charge isomers of recombinant mouse PI-TP␣ confirmed that the PC-containing isomer was the better substrate. Phosphoamino acid analysis of in vitro and in vivo 32 P-labeled PI-TP␣s showed that serine was the major site of phosphorylation. Degradation of 32 P-labeled PI-TP␣ by cyanogen bromide followed by high pressure liquid chromatography and sequence analysis yielded one 32 P-labeled peptide (amino acids 104 -190). This peptide contained Ser-148, Ser-152, and the consensus PKC phosphorylation site Ser-166. Replacement of Ser-166 with an alanine residue confirmed that indeed this residue was the site of phosphorylation. This mutation completely abolished PI and PC transfer activity. This was also observed when Ser-166 was replaced with Asp, implying that this is a key amino acid residue in regulating the function of PI-TP␣. Stimulation of NIH3T3 fibroblasts by phorbol ester or platelet-derived growth factor induced the rapid relocalization of PI-TP␣ to perinuclear Golgi structures concomitant with a 2-3-fold increase in lysophosphatidylinositol levels. This relocalization was also observed for Myc-tagged wtPI-TP␣ expressed in NIH3T3 cells. In contrast, the distribution of Myc-tagged PI-TP␣(S166A) and Myc-tagged PI-TP␣(S166D) were not affected by phorbol ester, suggesting that phosphorylation of Ser-166 was a prerequisite for the relocalization to the Golgi. A model is proposed in which the PKC-dependent phosphorylation of PI-TP␣ is linked to the degradation of PI.

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“…This is especially critical in various signal transduction cascades of cell-surface receptors, which require rapid production and turnover of phospholipid second messengers, in particular, of phosphoinositides (Toker 2002). The involvement of LTPs in receptor-mediated signal transduction cascades has been shown by many studies (Cockcroft 1997(Cockcroft , 1998Wang et al 2005). Most remarkable is the role of PITPs, which facilitate the monomeric exchange of either PI or PC between membranes in vitro.…”

Section: Nonvesicular Transport Of Phospholipids In Intact Cellsmentioning

confidence: 99%

Nonvesicular Lipid Transfer from the Endoplasmic Reticulum

Lev

2012

Cold Spring Harbor Perspectives in Biology

103

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Phosphatidylinositol transfer proteins: requirements in phospholipase C signaling and in regulated exocytosis

Cited by 19 publications

References 31 publications

Differential Regulation of Two Arabidopsis Type III Phosphatidylinositol 4-Kinase Isoforms. A Regulatory Role for the Pleckstrin Homology Domain

Differential Regulation of Two Arabidopsis Type III Phosphatidylinositol 4-Kinase Isoforms. A Regulatory Role for the Pleckstrin Homology Domain

The Protein Kinase C-dependent Phosphorylation of Serine 166 Is Controlled by the Phospholipid Species Bound to the Phosphatidylinositol Transfer Protein α

Nonvesicular Lipid Transfer from the Endoplasmic Reticulum

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