Regulates the phosphatidylinositol (4,5)-diphosphate levels on the cytoplasmic surface of the endoplasmic reticulum and thereby regulates secretion. Does not utilize phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2), nor phosphatidylinositol 3-phosphate (PtdIns(3)P) and phosphatidylinositol 4-phosphate (PtdIns(4)P).
TY - JOUR. T1 - Novel inhibitors of AKT. T2 - Assessment of a different approach targeting the pleckstrin homology domain. AU - Meuillet, E. J.. PY - 2011/6/1. Y1 - 2011/6/1. N2 - Protein kinase B/AKT plays a central role in cancer. The serine/threonine kinase is over-expressed or constitutively active in many cancers and has been validated as a therapeutic target for cancer treatment. However, targeting the kinase activity has revealed itself to be a challenge due to non-selectivity of the compounds towards other kinases. This review summarizes other approaches scientists have developed to inhibit the activity and function of AKT. They consist of targeting the pleckstrin homology (PH) domain of AKT. Indeed, upon the generation of 3-phosphorylated phosphatidylinositol phosphates (PI3Ps) by PI3-kinase (PI3K), AKT translocates from the cytosol to the plasma membrane and binds to the PI3Ps via its PH domain. Thus, several analogs of PI3Ps (PI Analogs or PIAs), alkylphospholipids (APLs), such as ...
Membrane-bound phosphatidylinositol-4 kinase (PI4-kinase) that catalyzes the phosphorylation of phosphatidylinositol (PI) to phosphatidylinositol 4-phosphate (PI4P), a lipid that plays important roles in endocytosis, Golgi function, protein sorting and membrane trafficking. Besides, phosphorylation of phosphatidylinositol (PI) to phosphatidylinositol 4-phosphate (PI4P) is the first committed step in the generation of phosphatidylinositol 4,5-bisphosphate (PIP2), a precursor of the second messenger inositol 1,4,5-trisphosphate (InsP3).
Class I phosphoinositide-3-kinase (PI3K) isoforms generate the intracellular signaling lipid, phosphatidylinositol(3,4,5)trisphosphate (PtdIns(3,4,5)P 3). PtdIns(3,4,5)P 3 regulates major aspects of cellular behavior, and the use of both genetic and pharmacological intervention has revealed important isoform-specific roles for PI3Ks in health and disease. Despite this interest, current methods for measuring PtdIns(3,4,5)P3 have major limitations, including insensitivity, reliance on radiolabeling, low throughput and an inability to resolve different fatty-acyl species. We introduce a methodology based on phosphate methylation coupled to high-performance liquid chromatographyg-mass spectrometry (HPLC-MS) to solve many of these problems and describe an integrated approach to quantify PtdIns(3,4,5)P3 and related phosphoinositides (regio-isomers of PtdInsP and PtdInsP2 are not resolved). This methodology can be used to quantify multiple fatty-acyl species of PtdIns(3,4,5)P3 in unstimulated mouse and human
Chemotactic cells generate localized accumulation of phosphoinositides at the leading edge of the cell. The lipids are then bound by lipid-binding domains of various signaling proteins. Dormann et al. used fusion proteins of green fluorescent protein (GFP) with the pleckstrin homology (PH) domains of various signaling proteins to monitor localized abundance of phosphoinositides during chemotaxis or phagocytosis in Dictyostelium. The specificity of the various PH domains for binding particular phosphoinositides enabled them to compare lipid signaling during the two processes. Concentrations of phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] accumulated at sites of engulfment during phagocytosis, as they do at the tip of cells facing an increasing gradient of chemoattractant. During chemotaxis, the phosphatase PTEN is thought to decrease concentrations of PtdIns(3,4,5)P3, but studies with cells lacking PTEN indicated it was not providing the same function during phagocytosis. ...
Kindlins co-activate integrins alongside talin. They possess, like talin, a FERM domain (4.1-erythrin-radixin-moiesin domain) comprising F0-F3 subdomains, but with a pleckstrin homology (PH) domain inserted in the F2 subdomain that enables membrane association. We present the crystal structure of murine kindlin-3 PH domain determined at a resolution of 2.23 Å and characterise its lipid binding using biophysical and computational approaches. Molecular dynamics simulations suggest flexibility in the PH domain loops connecting β-strands forming the putative phosphatidylinositol phosphate (PtdInsP)-binding site. Simulations with PtdInsP-containing bilayers reveal that the PH domain associates with PtdInsP molecules mainly via the positively charged surface presented by the β1-β2 loop and that it binds with somewhat higher affinity to PtdIns(3,4,5)P3 compared with PtdIns(4,5)P2 Surface plasmon resonance (SPR) with lipid headgroups immobilised and the PH domain as an analyte indicate affinities of 300 µM
Phosphatidylinositol-3-kinase (PI3K) is a lipid kinase and generates phosphatidylinositol-3,4,5-trisphosphate (PI(3, 4, 5)P3). PI(3, 4, 5)P3 is a second messenger essential for the translocation of Akt to the plasma membrane where it is phosphorylated and activated by phosphoinositide-dependent kina …
The molecular mechanism by which cAMP mediates PI(3,4,5)P3 accumulation upgradient in D. discoideum cells has been well described. PI3K is activated and enriched upgradient in the cell, whereas the PI(3,4,5)P3-degrading enzyme PTEN strongly localizes downgradient in the cell (Funamoto et al., 2002; Iijima and Devreotes, 2002). PTEN has been demonstrated to bind to phosphatidylinositol-3,4,5-trisphosphate (PI[4,5]P2), suggesting that PI(4,5)P2 is depleted upgradient in the cell (Iijima et al., 2004). This depletion of PI(4,5)P2 could be induced by several nonexclusive methods, such as the observed conversion of PI(4,5)P2 to PI(3,4,5)P3 upgradient by PI3K (Funamoto et al., 2002; Huang et al., 2003), but also by the conversion of PI(4,5)P2 to Ins(1,4,5)P3 and DAG by PLC, which is known to be activated by cAMP (Drayer and van Haastert, 1992; Bominaar et al., 1994). We propose a mechanism by which 8CPT-cAMP could revert the polarity of chemotactic sensing that is based on the observation that cAMP ...
Phosphatidylinositol-4,5-bisphosphate (PI-4,5-P2), the principal substrate for phosphoinositide 3-kinase (PI3K), is generated largely by type 1 phosphatidylinositol phosphate (PIP) kinases but can also be produced from PI-5-P at intracellular membranes by the type 2 family of PIP kinases known as phosphatidylinositol-5-phosphate 4-kinases (PI5P4K). The PI5P4Kβ enzyme (encoded by PIP4K2B) has been implicated in cellular stress responses and inhibition of AKT, but the role of PI5P4Ks in tumorigenesis remains unknown. Emerling and colleagues found amplification of PIP4K2B and elevated expression of PI5P4Kα and PI5P4Kβ proteins in a subset of breast tumors, in particular those with ERBB2 amplification or TP53 mutation or deletion. Depletion of both PI5P4Kα and PI5P4Kβ specifically suppressed the proliferation of HER2-positive, TP53-mutant breast cancer cells and impaired xenograft tumor formation; this growth-inhibitory phenotype was dependent on loss of p53 function and was associated with ...
The present experiments demonstrate that PH domains which bind PtdIns(4,5)P2 with high affinity and specificity, such as that of PLCδ1, can be used to visualize certain PtdIns(4,5)P2 pools in single living cells. Decreasing the affinity of the PH domain by mutation of any one of three basic residues known to form contacts with the inositol phosphate headgroup (12, 35) was sufficient to eliminate membrane localization of the construct. Also, PH domains with lower affinity for PtdIns(4,5)P2 such as that of the GTP-binding protein, dynamin, or with different specificity such as those of the Brutons tyrosine kinase and the protein kinase, Akt, did not show the clear plasma membrane localization that was observed with the PLCδ PH domain. The high concentration of the fluorescent probe at the plasma membrane was consistent with previously established views that PtdIns(4,5)P2 is most abundant in the plasma membrane (26). The lack of localization to intracellular membranes, including the nuclear ...
Golgi phosphatidylinositol-4-kinase effector and PtdIns4P sensor; interacts with the cytosolic domains of cis and medial glycosyltransferases, and in the PtdIns4P-bound state mediates the targeting of these enzymes to the Golgi; interacts with the catalytic domain of Sac1p, the major cellular PtdIns4P phosphatase, to direct dephosphosphorylation of the Golgi pool of PtdIns4P; tetramerization required for function; ortholog of human GOLPH3/GPP34/GMx33 ...
The Shc-like PID specifically binds to the Asn-Pro-Xaa-Tyr(P) motif found in many tyrosine-phosphorylated proteins including growth factor receptors. On the other hand the Dab-like PID domain binds to non-phosphorylated tyrosine residue or even a phenylalanine at the same position [ (PUBMED:7534213) ]. Most of the ligands for Shc-like PID domains are RTK or cytokine, whereas phosphotyrosine independent Dab-like PID domains seems to mediate other types of signaling pathways, like endocytosis/processing or exocytosis. This domain binds both peptides and headgroups of phosphatidylinositides, utilising two distinct binding motifs to mediate spatial organisation and localisation within cells [ (PUBMED:15567406) (PUBMED:7534213) (PUBMED:7527937) (PUBMED:7798194) ]. The 3D structure of PID domain has been solved [ (PUBMED:12737822) ]. It shares a folding pattern, commonly referred to as the PH-domain superfold. The core superfold consists of seven antiparallel beta strands forming two orthogonal ...
The Shc-like PID specifically binds to the Asn-Pro-Xaa-Tyr(P) motif found in many tyrosine-phosphorylated proteins including growth factor receptors. On the other hand the Dab-like PID domain binds to non-phosphorylated tyrosine residue or even a phenylalanine at the same position [ (PUBMED:7534213) ]. Most of the ligands for Shc-like PID domains are RTK or cytokine, whereas phosphotyrosine independent Dab-like PID domains seems to mediate other types of signaling pathways, like endocytosis/processing or exocytosis. This domain binds both peptides and headgroups of phosphatidylinositides, utilising two distinct binding motifs to mediate spatial organisation and localisation within cells [ (PUBMED:15567406) (PUBMED:7534213) (PUBMED:7527937) (PUBMED:7798194) ]. The 3D structure of PID domain has been solved [ (PUBMED:12737822) ]. It shares a folding pattern, commonly referred to as the PH-domain superfold. The core superfold consists of seven antiparallel beta strands forming two orthogonal ...
Pbp1p Binding Protein; Interacts Strongly With Pab1p-binding Protein 1 (Pbp1p) In The Yeast Two-hybrid System; Also Interacts With Lsm12p In A Copurification Assay; Relative Distribution To The Nucleus Increases Upon DNA Replication Stress
To determine relative affinities, we measured the binding of 32P-labeled phosphoinositides to the GST-Akt PH domain (amino acids 1 through 106) fusion protein in the presence of various concentrations of unlabeled phosphoinositides (17). DiC16PtdIns-3,4-P2 displaced binding of [32P]PtdIns-3,4-P2 to the Akt PH domain with 50% maximal effect at ∼5 μM. DiC16PtdIns-3,4,5-P3 competed for binding at higher concentrations, but PtdIns-4,5-P2 did not compete at concentrations up to 100 μM (Fig. 5A). Similar results were observed with displacement of [32P]PtdIns-3,4,5-P3 (9). Inositol-1,3,4-trisphosphate competed for binding of [32P] PtdIns-3,4-P2 with a ,50% maximal effect at 100 μM (9), whereas inositol-1,4,5-trisphosphate and inositol-1,3,4,5-tetrakisphosphate did not compete at this concentration. Inositol-1,3,4-trisphosphate failed to specifically stimulate Akt activity at these concentrations (9).. Full-length Akt AH domain (amino acids 1 through 147) protein bound somewhat better to ...
Lipid droplets (LDs) are evolutionarily conserved organelles that play important roles in cellular metabolism. Each LD is enclosed by a monolayer of phospholipids, distinct from bilayer membranes. During LD biogenesis and growth, this monolayer of lipids expands by acquiring phospholipids from the endoplasmic reticulum (ER) through nonvesicular mechanisms. Here, in a mini-screen, we find that ORP5, an integral membrane protein of the ER, can localize to ER-LD contact sites upon oleate loading. ORP5 interacts with LDs through its ligand-binding domain, and ORP5 deficiency enhances neutral lipid synthesis and increases the size of LDs. Importantly, there is significantly more phosphatidylinositol-4-phosphate (PI(4)P) and less phosphatidylserine (PS) on LDs in ORP5-deficient cells than in normal cells. The increased presence of PI(4)P on LDs in ORP5-deficient cells requires phosphatidylinositol 4-kinase 2-α. Our results thus demonstrate the existence of PI(4)P on LDs and suggest that LD-associated ...
The IUPHAR/BPS Guide to Pharmacology. phosphatidylinositol-5-phosphate 4-kinase type 2 beta - Phosphatidylinositol phosphate kinases. Detailed annotation on the structure, function, physiology, pharmacology and clinical relevance of drug targets.
Yeast and mammalian septins associate with biological membranes through a highly conserved polybasic region at the N-terminus of the GTP-binding domain (Fig. 2A). Through this region, recombinant yeast septins associate preferentially with phosphatidylinositol (4)-phosphate [PtdIns(4)P] and phosphatidylinositol (5)-phosphate [PtdIns(5)P], whereas recombinant SEPT4 specifically binds phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2] and phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P3] (Casamayor and Snyder, 2003; Zhang et al., 1999). In yeast cells that exhibit defective PtdIns(4)P synthesis, septins fail to assemble properly at the mother-bud neck (Casamayor and Snyder, 2003). In mammalian cells, sequestration of PtdIns(4,5)P2 and reduction of its overall level at the membrane leads to the loss of SEPT4 filaments (Zhang et al., 1999), and lipid-based signaling events and PtdIns(4,5)P2-mediated regulation of the actin cytoskeleton might indirectly influence septin ...
PIP5K isoforms appear to play multiple roles in the phagocytic process. A recent study found that PIP5K-γ influences the ability of phagocytic receptors to cluster after ligand engagement (Mao et al., 2009). This step precedes and is essential for the subsequent rearrangement of actin via WASP and Arp2/3, a complex event that requires PIP5K-α. Actin undergoes an acute biphasic change during phagocytosis: it is initially polymerized at sites of particle contact and pseudopod protrusion and is then disassembled from the base of the phagocytic cup (Botelho et al., 2000). Disassembly is required for proper sealing and internalization of the target particles and also likely for fusion with endomembranes (OReilly et al., 2003; Scott et al., 2005). PI4,5P2 appears to play a key role in both phases of actin remodelling: polymerization is accompanied by an increase in the local concentration of PI4,5P2, whereas the phosphoinositide virtually disappears from the base of the phagosome as actin ...
The relationship between receptor binding of the formylated peptide chemoattractant formylmethionylleucylphenylalanine (fMet-Leu-Phe), lysosomal enzyme secretion and metabolism of membrane phospholipids was evaluated in both human polymorphonuclear leucocytes (PMN) and the dimethyl sulphoxide (Me2SO)-stimulated human myelomonocytic HL-60 leukaemic cell line. In both cell types, exposure to fMet-Leu-Phe (100 nM) induced rapid lysosomal enzyme secretion (maximal release less than 30 s) and marked changes in the 32P-labelling of the inositol lipids phosphatidylinositol (PtdIns), phosphatidylinositol 4-phosphate (PtdIns4P), phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] as well as phosphatidic acid (PtdA). Specifically, levels of [32P]PtdIns and [32P]PtdIns(4,5)P2 decreased rapidly (peak decrease at 10-15s), with a subsequent increase at 30 s and later. PtdIns4P and PtdA showed only an increase. In Me2SO-differentiated HL-60 cells prelabelled with [3H]inositol for 20 h, fMet-Leu-Phe caused a ...
Downstream of tyrosine kinase (Dok) proteins Dok-1 and Dok-2 are involved in T cell homeostasis maintenance. Dok protein tyrosine phosphorylation plays a key role in establishing negative feedback loops of T cell signaling. These structurally related adapter molecules contain a pleckstrin homology (PH) domain generally acting as a lipid/protein-interacting module. We show that the presence of this PH domain is necessary for the tyrosine phosphorylation of Dok proteins and their negative functions in T cells. We find that Dok-1/Dok-2 PH domains bind in vitro to the rare phosphoinositide species, phosphatidylinositol 5-phosphate (PtdIns5P). Dok tyrosine phosphorylation correlates with PtdIns5P production in T cells upon TCR triggering. Furthermore, we demonstrate that PtdIns5P increase regulates Dok tyrosine phosphorylation in vivo. Together, our data identify a novel lipid mediator in T cell signaling and suggest that PH-PtdIns5P interactions regulate T cell responses.
Many signaling, cytoskeletal, and transport proteins have to be localized to the plasma membrane (PM) in order to carry out their function. We surveyed PM-targeting mechanisms by imaging the subcellular localization of 125 fluorescent protein-conjugated Ras, Rab, Arf, and Rho proteins. Out of 48 proteins that were PM-localized, 37 contained clusters of positively charged amino acids. To test whether these polybasic clusters bind negatively charged phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] lipids, we developed a chemical phosphatase activation method to deplete PM PI(4,5)P2. Unexpectedly, proteins with polybasic clusters dissociated from the PM only when both PI(4,5)P2 and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] were depleted, arguing that both lipid second messengers jointly regulate PM targeting. ...
PIKfyve, a FYVE finger-containing phosphoinositide kinase, is an enzyme that in humans is encoded by the PIKFYVE gene. The principal enzymatic activity of PIKfyve is to phosphorylate PtdIns3P to PtdIns(3,5)P2. PIKfyve activity is responsible for the production of both PtdIns(3,5)P2 and phosphatidylinositol 5-phosphate (PtdIns5P). PIKfyve is a large protein, containing a number of functional domains and expressed in several spliced forms. The reported full-length mouse and human cDNA clones encode proteins of 2052 and 2098 amino acid residues, respectively. By directly binding membrane PtdIns(3)P, the FYVE finger domain of PIKfyve is essential in localizing the protein to the cytosolic leaflet of endosomes. Impaired PIKfyve enzymatic activity by dominant-interfering mutants, siRNA- mediated ablation or pharmacological inhibition causes endosome enlargement and cytoplasmic vacuolation due to impaired PtdIns(3,5)P2 synthesis. Thus, via PtdIns(3,5)P2 production, PIKfyve participates in several ...
This enzyme hydrolyses 1-phosphatidyl-1D-myo-inositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) to produce PtdIns(3,4)P2, thereby negatively regulating the PI3K (phosphoinositide 3-kinase) pathways. The enzyme also shows activity toward (PtdIns(1,3,4,5)P4) [5]. The enzyme is involved in several signal transduction pathways in the immune system leading to an adverse range of effects ...
The following pictures illustrate how the lipids must move apart to accommodate the insertion of helix zero. The first picture shows 2 different views of the ENTH domain with a space filled PtdIns(4,5)P2 docked in the structure. In the bottom picture a membrane (to scale) is added such that the PtdIns(4,5)P2 is inserted and consequently helix zero is buried. One can image a space filled helix zero an d the number of lipids that would have to be displaced to accommodate epsin docking on the membrane ...
Pleckstrin homology (PH) domains are small protein modules known for their ability to bind phosphoinositides and to drive membrane recruitment of their host proteins. We investigated phosphoinositide binding (in vitro and in vivo) and subcellular localization, and we modeled the electrostatic proper …
Order Anti-human phosphatidylinositol-3-phosphate phosphatidylinositol 5-kinase type III PAb 02012560599 at Gentaur phosphatidylinositol-3-phosphate/phosphatidylinositol 5-kinase, III PAb
TY - JOUR. T1 - The regulation of membrane to cytosol partitioning of signalling proteins by phosphoinositides and their soluble headgroups. AU - Downes, C Peter. AU - Gray, Alexandra. AU - Fairservice, A. AU - Safrany, S T. AU - Batty, Ian H. AU - Fleming, Ian Neil. PY - 2005/12. Y1 - 2005/12. N2 - Inositol phospholipids [PIs (phosphoinositides)] represent a group of membrane-tethered signalling molecules which differ with respect to the number and distribution of monoester phosphate groups around the inositol ring. They function by binding to proteins which possess one of several domains that bind a particular PI species, often with high affinity and specificity. PH (pleckstrin homology) domains for example possess ligand-binding pockets that are often lined with positively charged residues and which bind PIs with varying degrees of specificity. Several PH domains bind not only PIs, but also their cognate headgroups, many of which occur naturally in cells as relatively abundant cytosolic ...
Tcell anergy is one of the mechanisms thought to act in the periphery to ensure tolerance to self. The term anergy was first used to describe T cell clones rendered unresponsive to subsequent restimulation by first activating them through the TCR (signal 1) without appropriate costimulation (signal 2) (1) or, more recently, using an altered peptide ligand for activation (2). The characteristic feature of this induced unresponsiveness was the inability of the anergic T cells to proliferate or produce IL-2 following subsequent optimal restimulation (3). Anergic T cells appeared to have a defect in signaling pathways upstream of transcription of the IL-2 gene (4, 5, 6). Additional studies demonstrated the presence of cis-dominant negative regulatory elements affecting IL-2 transcription (7, 8). The recent finding of increased general receptor of phosphoinositides-1 expression indicated that broader genetic changes may accompany the induction and maintenance of the anergic phenotype (9). Our ...
In this study, we demonstrate a previously unrecognized role for PPIP5K1 in regulating cell death in response to genotoxic stress. We observed that overexpression of PPIP5K1 in HEK 293 cells protected them from apoptosis triggered by etoposide and other agents, in contrast to overexpression of another InsPP -generating enzyme, IP6K2, which sensitizes cells to cytotoxic agents [5, 6, 7, 22, 2322, 23]. After measuring the impact of PPIP5K1 on an array of apoptosis-related proteins, we also observed that PPIP5K1 alters phosphorylation of p53 at three key residues, which suggests a mechanism through which PPIP5K1 acts.. We observed the protection provided by PPIP5K1 to be dependent on the production of InsPP, as the anti-apoptotic activity provided was lost in cells expressing a kinase-impaired mutant. Previous reports have indicated that total cellular levels of InsPP are not significantly affected by over expression of PPIP5K1. We therefore cannot unambiguously conclude that it is the production ...
The regulation of the synthesis of PtdIns(4,5)P2 is emerging as being as complex as we might expect from the multi-functional nature of this lipid. In the present chapter we focus on one aspect of inositide metabolism, which is the functions of the Type II PIPkins (Type II PtdInsP kinases). These are primarily PtdIns5P 4-kinases, although in vitro they will also phosphorylate PtdIns3P to PtdIns(3,4)P2. Thus they have three, not necessarily exclusive, functions: to make PtdIns(4,5)P2 by a quantitatively minor route, to remove PtdIns5P and to make PtdIns(3,4)P2 by a route that does not involve a Class I PtdIns 3-kinase. None of these three possible functions has yet been unambiguously proven or ruled out. Of the three isoforms, α and β are widely expressed, the IIα being predominantly cytosolic and the IIβ primarily nuclear. PIPkin IIγ has a much more restricted tissue expression pattern, and appears to be localized primarily to intracellular vesicles. Here we introduce in turn each of the ...
The list of Phosphatidylcholine products offered by Avanti is designed to provide compounds having a variety of physical properties. Products available include
The phosphatidylinositol phosphate kinases (PIPkins) are a family of enzymes involved in regulating levels of several functionally important inositol phospholipids within cells. The PIPkin family is subdivided into three on the basis of substrate specificity, each subtype presumably regulating levels of different subsets of the inositol lipids. The physiological function of the type II isoforms, which exhibit a preference for phosphatidylinositol 5-phosphate, a lipid about which very little is known, is particularly poorly understood. In the present study, we demonstrate interaction between, and co-immunoprecipitation of, type IIα PIPkin with the related, but biochemically and immunologically distinct, type I PIPkin isoforms. Type IIα PIPkin interacts with all three known type I PIPkins (α, β and γ), and in each case co-expression of the type I isoform with type IIα results in recruitment of the latter from the cytosol to the plasma membrane of the cell. This change in subcellular ...
Resnick et al. provide new insight into the biological roles of the enzyme inositol polyphosphate multikinase (IPMK, also called Ipk2). The protein was so named because it phosphorylates multiple sites on water-soluble inositol polyphosphate rings. However, Resnick et al. show that in vitro and in vivo, IPMKs from yeast and mammals have lipid inositol kinase activity. This activity is highly specific for the D-3 position of the inositol ring--even more so than the better known phosphoinositide 3-kinases (PI3Ks), which, in mammals, generate phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] in response to activated receptor tyrosine kinases. Unlike PI3K, though, IPMK was found almost exclusively in the nucleus of transfected yeast or human cells. IPMK had been previously implicated in control of gene expression in yeast, and Resnick et al. used experiments in yeast lacking phospholipase C (which consequently have no highly phosphorylated soluble inositol polyphosphates) to show that ...
Salinity is a major constraint for intrinsically salt sensitive grain legume chickpea. Chickpea exhibits large genetic variation amongst cultivars, which show better yields in saline conditions but still need to be improved further for sustainable crop production. Based on previous multi-location physiological screening, JG 11 (salt tolerant) and ICCV 2 (salt sensitive) were subjected to salt stress to evaluate their physiological and transcriptional responses. A total of ~480 million RNA-Seq reads were sequenced from root tissues which resulted in identification of 3,053 differentially expressed genes (DEGs) in response to salt stress. Reproductive stage shows high number of DEGs suggesting major transcriptional reorganization in response to salt to enable tolerance. Importantly, cationic peroxidase, Aspartic ase, NRT1/PTR, phosphatidylinositol phosphate kinase, DREB1E and ERF genes were significantly up-regulated in tolerant genotype. In addition, we identified a suite of important genes ...
The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental
Sorting nexin 27 (SNX27) controls the endosomal to cell-surface recycling of diverse transmembrane protein cargos. Critical to this function is the recruitment of SNX27 to endosomes through the binding of phosphatidylinositol-3-phosphate (PtdIns3P) by the phox-homology (PX) domain. In T cells, SNX27 is polarized to the immunological synapse (IS) in an activation-dependent manner, but the molecular mechanisms underlying SNX27 translocation remain to be clarified. Here, we examined the phosphoinositide lipid-binding capabilities of full-length SNX27, and discovered a novel PtdInsP binding site within the C-terminal 4.1/ezrin/radixin/moesin (FERM) domain. This binding site showed a clear preference for di and tri-phosphorylated phophoinositides, and the interaction was confirmed through biophysical, mutagenesis and modeling approaches. At the IS of activated T-cells cell signaling regulates phosphoinositide dynamics, and we find that perturbing phosphoinositide binding by the SNX27 FERM domain ...
Anionic phospholipids include phosphatidic acid (PA), phosphatidylserine (PS), phosphatidylinositol (PI), and its phosphorylated derivatives the phosphoinositides (e.g. phosphatidylinositol-4-phosphate (PI4P) or phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2)). Although they are low abundant lipids, they are particularly important for membrane functions. In particular, anionic lipids act as biochemical and biophysical landmarks that contribute to the establishment of membrane identity, signaling activities, and compartment morphodynamics. Each anionic lipid accumulates in different endomembranes according to a unique subcellular pattern, where they locally provide docking platforms for proteins. As such, they are mostly believed to act in the compartments in which they accumulate. However, mounting evidence throughout eukaryotes suggests that anionic lipids are not as compartment-specific as initially thought and that they are instead organized as concentration gradients across different organelles.
The phosphatidylinositol 3-kinase (PI3K) signalling pathway is one of the most frequently genetically altered pathways in human cancers (Samuels et al., 2004). Class I PI3Ks are lipid kinases that bind to the cell membrane and phosphorylate the lipid substrate, phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2), in order to produce the second messenger, PIP3. In turn, this regulates several biological signalling pathways involved in cell growth, proliferation, differentiation, and survival (Qiu et al., 1998; Roche, Koegl, & Courtneidge, 1994; Yao & Cooper, 1995). The work in this thesis explores how different PI(4,5)P2 fatty acyl chain arrangements and specific PI3K amino acids can affect membrane binding interactions and catalysis events for both wild-type (WT) and oncogenic class I PI3Ks. Firstly, the effects of different PI(4,5)P2 lipid species were investigated on PI3K lipid kinase activity using biochemical methods, and on PI3K membrane binding using biophysical methods. The influences of ...
Proteins encoding phosphotyrosine binding (PTB) domains function as adaptors or scaffolds to organize the signaling complexes involved in wide-ranging physiological processes including neural development, immunity, tissue homeostasis and cell growth. Due to structural differences, PTB domains are divided into three groups represented by phosphotyrosine-dependent IRS-like, phosphotyrosine-dependent Shc-like (see ,PDOC00907,), and phosphotyrosine-independent Dab-like PTBs (see ,PDOC00907,). IRS-type PTB domain has an average length of about 100 amino acids. It binds to the insulin receptor through the Asn-Pro-Xaa-Tyr(P) motif found in many tyrosine-phosphorylated proteins. This domain is found in IRS/Dok/SNT proteins that are the major adapters for RTK and cytokine signaling. This domain binds both peptides and headgroups of phosphatidylinositides, utilizing two distinct binding motifs to mediate spatial organization and localization within cells. The IRS-type PTB domain is found alone or in ...
UW-Madison researchers have identified novel PAPs that interact with phosphoinositide signaling molecules. These new PAPs, called phosphatidylinositol phosphate (PIP)-PAPs, provide a new nuclear regulatory mechanism, and therefore a new means of controlling and regulating protein expression. Unlike known PAPs, the activity of these PIP-PAPs may be directly modulated by components of phosphatidylinositol-based signaling pathways, which play crucial roles in the regulation of cell processes at the plasma membrane and in the nucleus ...
Ins(1,4,5)P3 is the intracellular messenger that in many cells mediates the effects of Ca2(+)-mobilizing receptors on intracellular Ca2+ stores. An Ins(1,4,5)P3 receptor from cerebellum has been purified and functionally reconstituted, but the relationship between this protein and the high-affinity Ins(1,4,5)P3-binding sites of peripheral tissues is unclear. We compared the Ins(1,4,5)P3-binding sites of liver and cerebellum by measuring inhibition of specific Ins(1,4,[32P]5)P3 binding by various ligands under equilibrium conditions, and find that each ligand binds with similar affinity in the two tissues. Earlier studies in which Ins(1,4,5)P3 binding and Ca2+ mobilization were measured under different conditions demonstrated large differences between KD values for binding and EC50 values (concn. giving half-maximal effect) for Ca2+ release. We show here that, when measured under identical conditions, KD and EC50 values for four agonists are similar. Schild analysis of inhibition of Ins(1,4,5)P3 ...
When cancer strikes, with many forms, researchers will see alterations in lipid metabolism. While this relationship is known, scientists still dont fully understand how lipids contribute to cellular transformations, tumour development and cancer spread.. At Ryerson, a research group in the Department of Chemistry and Biology set out to study one particular type of lipid, namely signaling phospholipids, also referred to as phosphoinositides. Leslie Bone, a student who is currently completing her PhD in Molecular Science at Ryerson, has dedicated her studies to learning more about how fats communicate within cells and how they can be involved in cancer progression. She was also the lead author of the phosphoinositides study, supervised by two Ryerson professors, Dr. Roberto Botelho and Dr. Costin Antonescu.. Asked to further explain the role of tiny signaling phospholipids, Bone says: Phosphoinositides are important for cellular processes such as cell migration and cell growth. The function of ...
Order GDP-mannose-dependent alpha- 1-6 -phosphatidylinositol dimannoside mannosyltransferase-E coli 01022698370 at Gentaur GDP-mannose-dependent alpha (1-6) phosphatidylinositol dimannoside mannosyltransferase
Phosphatidylinositol 4,5-biphosphate (PIP2) has been proposed to act as a second messenger in the regulation of many cell processes. If so, then PIP2 should fulfill two important criterias: first PIP2 levels should vary spatially or temporally under physiological conditions, and secondly, these variations should suffice to influence cellular processes. In this thesis we have addressed the issue and provide data that support the idea that PIP2 can function as a second messenger, since PIP2 levels were found to vary significantly over time affecting cell survival, as well as cortical actin dynamics. Interestingly, these results also suggest that PIP2 influences multiple physiological processes within the same cell, apparently with spatial resolution. This view also prevails in the literature: it is widely hypothesized that the plasma membrane contains spatially confined PIP2 pools or domains. Indeed, recent studies that used GFP-tagged pleckstrin homology domains (GFP-PH) as fluorescent PIP2 ...
a unique N-terminal hydrophobic extension that lies on the cytosolic membrane surface of the lysosome, where it interacts with the lysosomal signaling lipids phosphatidic acid (PA) and phosphatidylinositol(3,5)bisphosphate [PI(3,5)P2] ...
Sigma-Aldrich offers abstracts and full-text articles by [Fubito Nakatsu, Jeremy M Baskin, Jeeyun Chung, Lukas B Tanner, Guanghou Shui, Sang Yoon Lee, Michelle Pirruccello, Mingming Hao, Nicholas T Ingolia, Markus R Wenk, Pietro De Camilli].
The p85 subunit of phosphatidylinositol 3-kinase interacts with the phosphodomain of TARP.a) Binding of CMTPX-labeled C. trachomatis L2 EBs to cells expressing
Phosphoinositides (PIs) are minor components on cytoplasmic sides of eukaryotic cell membranes, but they play important roles in many...
Trouvez tous les livres de Stenmark, Harald (ed.) - Phosphoinositides in Subcellular Targeting and Enzyme Activation. Sur eurolivre.fr,vous pouvez commander des livres anciens et neufs.COMPARER ET acheter IMMÉDIATEMENT au meilleur prix. 9783540009504
WR304 is an antibody that binds specifically to the lipids PIP and PIP2. WR304 also neutralizes infectious HIV-1 virus and can be used to probe the presence of
1OCS: Crystal Structure of the Yeast Phox Homology (Px) Protein Grd19P (Sorting Nexin 3) Complexed to Phosphatidylinositol-3-Phosphate
多种适用的PIP5K1BELISA试剂盒,如等。在antibodies-online.cn对比PIP5K1BELISA试剂盒,以便找到您需要的产品。