Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A family of phospholipase C-related, catalytically inactive proteins (designated PRIP) have been identified as a group of novel inositol 1,4,5-trisphosphate binding proteins with a domain organization similar to phospholipase C-delta but lacking the enzymatic activity. The PRIP family consists of at least two types of proteins (PRIP-1 and PRIP-2 subfamilies). In the present study, we examined the tissue distribution of PRIP-2, its expression in rat brain at the mRNA level, and the characteristics of its binding to inositol compounds, protein phosphatase 1, and gamma-amino butyric acid receptor associated protein. We also compared these characteristics with those of PRIP-1. Northern blot analysis and reverse-transcription polymerase chain reaction showed that PRIP-1 was present mainly in the brain, whereas PRIP-2 was expressed ubiquitously. In situ hybridization studies using rat brain revealed that the mRNA for both PRIP-1 and PRIP-2 was similarly expressed; it was detected in the granular cell and Purkinje cell layers in the cerebellum, and in the hippocampal pyramidal cells, dentate granule cells, and pyramidal and/or granule cells of the cerebral cortex in the cerebrum. PRIP-2 bound inositol 1,4,5-trisphosphate and its parent lipid, phosphatidylinositol 4,5-bisphosphate, with a similar affinity, while PRIP-1 preferentially bound the former ligand by about 10-fold. PRIP-1 and PRIP-2 interacted with protein phosphatase 1 and gamma-amino butyric acid receptor associated protein in a similar manner. These results indicate that, similar to PRIP-1, PRIP-2 may be involved in both inositol 1,4,5-trisphosphate-mediated and gamma-amino butyric acid-related signaling.
 ...
PMID:Molecules interacting with PRIP-2, a novel Ins(1,4,5)P3 binding protein type 2: Comparison with PRIP-1. 1246 85

PRIP-1 was isolated as a novel inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] binding protein with a domain organization similar to phospholipase C-delta1 (PLC-delta1) but lacking the enzymatic activity. Further studies revealed that the pleckstrin homology (PH) domain of PRIP-1 is the region responsible for binding Ins(1,4,5)P3. In this study we aimed to clarify the role of PRIP-1 at the physiological concentration in Ins(1,4,5)P3-mediated Ca2+ signaling, as we had previously used COS-1 cells overexpressing PRIP-1 (Takeuchi et al., 2000, Biochem J 349:357-368). For this purpose we employed PRIP-1 knock out (PRIP-1-/-) mice generated previously (Kanematsu et al., 2002, EMBO J 21:1004-1011). The increase in free Ca2+ concentration in response to purinergic receptor stimulation was lower in primary cultured cortical neurons prepared from PRIP-1-/- mice than in those from wild type mice. The relative amounts of [3H]Ins(1,4,5)P3 measured in neurons labeled with [3H]inositol was also lower in cells from PRIP-1-/- mice. In contrast, PLC activities in brain cortex samples from PRIP-1-/- mice were not different from those in the wild type mice, indicating that the hydrolysis of Ins(1,4,5)P3 is enhanced in cells from PRIP-1-/- mice. In vitro analyses revealed that type1 inositol polyphosphate 5-phosphatase physically interacted with a PH domain of PRIP-1 (PRIP-1PH) and its enzyme activity was inhibited by PRIP-1PH. However, physical interaction with these two proteins did not appear to be the reason for the inhibition of enzyme activity, indicating that binding of Ins(1,4,5)P3 to the PH domain prevented its hydrolyzation. Together, these results indicate that PRIP-1 plays an important role in regulating the Ins(1,4,5)P3-mediated Ca2+ signaling by modulating type1 inositol polyphosphate 5-phosphatase activity through binding to Ins(1,4,5)P3.
 ...
PMID:Role of PRIP-1, a novel Ins(1,4,5)P3 binding protein, in Ins(1,4,5)P3-mediated Ca2+ signaling. 1546 68

Investigation of chemically synthesized inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] analogs has led to the isolation of a novel binding protein with a molecular size of 130 kDa, characterized as a molecule with similar domain organization to phospholipase C-d1 (PLC-d1) but lacking the enzymatic activity. An isoform of the molecule was subsequently identified, and these molecules have been named PRIP (PLC-related, but catalytically inactive protein), with the two isoforms named PRIP-1 and -2. Regarding its ability to bind Ins(1,4,5)P3 via the pleckstrin homology domain, the involvement of PRIP-1 in Ins(1,4,5)P3-mediated Ca2+ signaling was examined using COS-1 cells overexpressing PRIP-1 and cultured neurons prepared from PRIP-1 knock-out mice. Yeast two hybrid screening of a brain cDNA library using a unique N-terminus as bait identified GABARAP (GABAA receptor associated protein) and PP1 (protein phosphatase 1), which led us to examine the possible involvement of PRIP in GABAA receptor signaling. For this purpose PRIP knock-out mice were analyzed for GABAA receptor function in relation to the action of benzodiazepines from the electrophysiological and behavioral aspects. During the course of these experiments we found that PRIP also binds to the b-subunit of GABAA receptors and PP2A (protein phosphtase 2A). Here, we summarize how PRIP is involved in Ins(1,4,5)P3-mediated Ca2+ signaling and GABAA receptor signaling based on the characteristics of binding molecules.
 ...
PMID:PRIP, a novel Ins(1,4,5)P3 binding protein, functional significance in Ca2+ signaling and extension to neuroscience and beyond. 1640 43

Brain-derived neurotrophic factor (BDNF) modulates several distinct aspects of synaptic transmission, including GABAergic transmission. Exposure to BDNF alters properties of GABA(A) receptors and induces changes in the expression level at the cell surface. Although phospholipase C-related inactive protein-1 (PRIP-1) plays an important role in GABA(A) receptor trafficking and function, its role in BDNF-dependent modulation of these receptors, together with the role of PRIP-2, was investigated using neurons cultured from PRIP double knock-out mice. The BDNF-dependent inhibition of whole cell GABA-evoked currents observed in wild type neurons was not detected in neurons cultured from knock-out mice. Instead, a gradual increase in GABA-evoked currents in these neurons correlated with a gradual increase in phosphorylation of GABA(A) receptor beta3 subunit in response to BDNF. To characterize the specific role(s) that PRIP plays as components of underlying molecular machinery, we examined the recruitment of protein phosphatase(s) to GABA(A) receptors. We demonstrate that PRIP associates with phosphatases as well as with beta subunits. PRIP was found to colocalize with GABA(A) receptor clusters in cultured neurons and with recombinant GABA(A) receptors when co-expressed in HEK293 cells. Importantly, a peptide mimicking a domain of PRIP involved in binding to beta subunits disrupted the co-localization of these proteins in HEK293 cells and potently inhibited the BDNF-mediated attenuation of GABA(A) receptor currents in wild type neurons. Together, the results suggest that PRIP plays an important role in BDNF-dependent regulation of GABA(A) receptors by mediating the specific association between beta subunits of these receptors with protein phosphatases.
 ...
PMID:Modulation of GABA(A) receptor phosphorylation and membrane trafficking by phospholipase C-related inactive protein/protein phosphatase 1 and 2A signaling complex underlying brain-derived neurotrophic factor-dependent regulation of GABAergic inhibition. 1675 70

PRIP, phospholipase C related, but catalytically inactive protein was first identified as a novel inositol 1,4,5-trisphosphate binding protein. It has a number of binding partners including protein phosphatase (PP1 and 2A), GABAA receptor associated protein, and the beta subunits of GABAA receptors, in addition to inositol 1,4,5-trisphosphate. The identification of these molecules led us to examine the possible involvement of PRIP in the phospho-regulation of the beta subunits of GABAA receptors using hippocampal neurons prepared from PRIP-1 and 2 double knock-out (DKO) mice. Experiments were performed with special reference to the dephosphorylation processes of the beta subunits. The phosphorylation of beta3 subunits by the activation of protein kinase A in cortical neurons of the control mice continued for up to 5 min, even after washing out of the stimulus, followed by a gradual dephosphorylation. That of DKO mice gradually increased in spite of the lower phosphorylation levels induced by the stimulation. There was little difference in the amount of cellular cyclic AMP and protein kinase A activity between the control and mutant mice, indicating that phosphatases such as PP1 and PP2A are primarily involved in the difference. The time course of PP1 activity changes in the vicinity of the receptors in control mice corresponded to the phosphorylation of PRIP, while that of the mutant mice decreased with the period of the incubation. This is a good agreement with the suggestion that PRIP binds to and inactivates PP1, which is regulated by the phosphorylation of PRIP at threonine 94. These results suggest that PRIP plays an important role in controlling the dynamics of GABAA receptor phosphorylation by through PP1 binding and, therefore, the efficacy of synaptic inhibition mediated by these receptors.
 ...
PMID:Protein phosphatase regulation by PRIP, a PLC-related catalytically inactive protein--implications in the phospho-modulation of the GABAA receptor. 1685 55

The PRIP [phospholipase C related, but catalytically inactive protein] family has been isolated as a novel inositol 1,4,5-trisphosphate binding protein with a domain organization similar to phospholipase C-delta but lacking the enzyme activity, comprising PRIP-1 and PRIP-2. The PRIP-1 gene is expressed predominantly in the brain, while PRIP-2 exhibits a relatively ubiquitous expression in rats and mice. We also found that PRIP-1 plays an important role in type A receptor signaling for gamma-aminobutyric acid in the brain. In this study, we investigated PRIP-1 gene structure and the possible mechanisms involved in the expression. The tissue distribution pattern of PRIP gene expression in humans was similar to that in rodents. 5'RACE (rapid amplification of cDNA ends) analysis using PRIP-1 gene specific primers with human brain mRNA revealed the presence of three new exons, indicating that the PRIP-1 gene is organized into 8 exons intervened by 7 introns. Although three transcripts resulting from the alternative splicing of exon 2 and/or 3 were detected, a transcript lacking exons 2 and 3 was predominantly expressed in humans, suggesting that the translation start codon of human PRIP-1 exists in exon 1. To characterize the human PRIP-1 promoter, transient luciferase assay was carried out with luciferase constructs including various lengths of the 5' flanking region of the PRIP-1 gene. The results indicated that the positive regulatory region is located -237 to -108 bp upstream from the transcription start site. Gel shift assay revealed the specific binding of some nuclear proteins to this region, suggesting that the existence of transcription factors contributes to the positive regulation of PRIP-1 gene expression. Mutation analyses revealed that the binding of a transcription factor, MAZ to the regulatory site leads to the promoter activity, indicating that MAZ is involved in the expression regulation of the human PRIP-1 gene.
 ...
PMID:Characterization of the human PRIP-1 gene structure and transcriptional regulation. 1695 28

gamma-Aminobutyric acid (GABA), an important inhibitory neurotransmitter in both vertebrates and invertebrates, acts on GABA receptors that are ubiquitously expressed in the CNS. GABA(A) receptors also represent a major site of action of clinically relevant drugs, such as benzodiazepines, barbiturates, ethanol, and general anesthetics. It has been shown that the intracellular M3-M4 loop of GABA(A) receptors plays an important role in regulating GABA(A) receptor function. Therefore, studies of the function of receptor intracellular loop associated proteins become important for understanding mechanisms of regulating receptor activity. Recently, several labs have used the yeast two-hybrid assay to identify proteins interacting with GABA(A) receptors, for example, the interaction of GABA(A) receptor associated protein (GABARAP) and Golgi-specific DHHC zinc finger protein (GODZ) with gamma subunits, PRIP, phospholipase C-related, catalytically inactive proteins (PRIP-1) and (PRIP-2) with GABARAP and receptor gamma2 and beta subunits, Plic-1 with some alpha and beta subunits, radixin with the alpha5 subunit, HAP1 with the beta1 subunit, GABA(A) receptor interacting factor-1 (GRIF-1) with the beta2 subunit, and brefeldin A-inhibited GDP/GTP exchange factor 2 (BIG2) with the beta3 subunit. These proteins have been shown to play important roles in modulating the activities of GABA(A) receptors ranging from enhancing trafficking, to stabilizing surface and internalized receptors, to regulating modification of GABA(A) receptors. This article reviews the current studies of GABA(A) receptor intracellular loop-associated proteins.
 ...
PMID:GABAA receptor associated proteins: a key factor regulating GABAA receptor function. 1708 46

The subunit composition of GABA(A) receptors is known to be associated with distinct physiological and pharmacological properties. Previous studies that used phospholipase C-related inactive protein type 1 knock-out (PRIP-1 KO) mice revealed that PRIP-1 is involved in the assembly and/or the trafficking of gamma2 subunit-containing GABA(A) receptors. There are two PRIP genes in mammals; thus the roles of PRIP-1 might be compensated partly by those of PRIP-2 in PRIP-1 KO mice. Here we used PRIP-1 and PRIP-2 double knock-out (PRIP-DKO) mice and examined the roles for PRIP in regulating the trafficking of GABA(A) receptors. Consistent with previous results, sensitivity to diazepam was reduced in electrophysiological and behavioral analyses of PRIP-DKO mice, suggesting an alteration of gamma2 subunit-containing GABA(A) receptors. The surface numbers of diazepam binding sites (alpha/gamma2 subunits) assessed by [3H]flumazenil binding were reduced in the PRIP-DKO mice as compared with those of wild-type mice, whereas the cell surface GABA binding sites (alpha/beta subunits, assessed by [3H]muscimol binding) were increased in PRIP-DKO mice. The association between GABA(A) receptors and GABA(A) receptor-associated protein (GABARAP) was reduced significantly in PRIP-DKO neurons. Disruption of the direct interaction between PRIP and GABA(A) receptor beta subunits via the use of a peptide corresponding to the PRIP-1 binding site reduced the cell surface expression of gamma2 subunit-containing GABA(A) receptors in cultured cell lines and neurons. These results suggest that PRIP is implicated in the trafficking of gamma2 subunit-containing GABA(A) receptors to the cell surface, probably by acting as a bridging molecule between GABARAP and the receptors.
 ...
PMID:Phospholipase C-related inactive protein is involved in trafficking of gamma2 subunit-containing GABA(A) receptors to the cell surface. 1730 Nov 77

GABA(A) receptors are heteropentameric ligand-gated chloride channels composed of a variety of subunits, including alpha1 - 6, beta1 - 3, gamma1 - 3, delta, epsilon, theta, and pi, and play a key role in controlling inhibitory neuronal activity. Modification of the efficacy of the synaptic strength is produced by changes in both the number of neuronal surface receptors and pentameric molecular assembly, leading to differences of sensitivity to neurotransmitters and neuromimetic drugs. Therefore, it is important to understand the molecular mechanisms regulating the so-called "life cycle of GABA(A) receptors" including sequential pentameric assembly at the site synthesized, intracellular transport through the Golgi apparatus and the cytoplasm, insertion into the cell membrane, functional modulation at the cell surface, and finally internalization, followed by either recycling back to the surface membrane or lysosomal degradation. This review is focused on events related to the surface expression of the receptor containing the gamma2 subunit and clathrin/AP2 complex-mediated phospho-regulated endocytosis of the receptor, with special reference to the function of novel GABA(A) receptor modulators, GABARAP (GABA(A) receptor-associated protein) and PRIP (phospholipase C-related, but catalytically inactive protein).
 ...
PMID:Regulation of GABA(A)-receptor surface expression with special reference to the involvement of GABARAP (GABA(A) receptor-associated protein) and PRIP (phospholipase C-related, but catalytically inactive protein). 1769 May 29

A well-known protein module regulating molecular interactions is the pleckstrin homology (PH) domain whose best-characterised ligand is phosphoinositide. In the present study, we analysed the PH domain from PRIP (phospholipase C-related but catalytically inactive protein, comprising types 1 and 2) regarding phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] binding employing a variety of binding assays. The PH domains prepared from PRIP-1 and -2 showed similar binding profiles to soluble ligands in vitro and showed similar plasma membrane localisation to that of PLC-delta1; however, the PH domain with the N-terminal extension of PRIP-1 but not PRIP-2 showed even distribution throughout the cytoplasm, indicating that the N-terminal extension of PRIP-1 inhibited binding to PtdIns(4,5)P(2) present in the plasma membrane. A chimeric molecule of PLC-delta1 PH domain with the N-terminal extension of PRIP-1 exhibited similar localisation to PRIP-1 PH domain with the N-terminal extension. Binding assay to liposomes containing various concentrations of PtdIns(4,5)P(2) revealed that the PH domain of PLC-delta1 bound steeply to the maximum, even at a concentration of 1.2 mol%, whereas the PH domains from PRIP-1 and -2 bound depending on the concentration up to 5 mol%. We also performed binding experiments using saponin-permeabilised PC12 cells. PH domains from PRIP increased the binding to cells preincubated with the brain cytosol extract in the presence of ATP, during which PtdIns(4,5)P(2) were probably synthesised. The binding of PH domain with the following EF hand motifs showed Ca(2+)-dependent binding. These results indicate that the PH domain of PRIP binds to PtdIns(4,5)P(2) present in the plasma membrane, depending on the concentrations of the lipid ligand and Ca(2+), suggesting that PRIP might play physiological roles in events involved in the changes of these parameters, probably including Ins(1,4,5)P(3).
 ...
PMID:Binding of phospholipase C-related but catalytically inactive protein to phosphatidylinositol 4,5-bisphosphate via the PH domain. 1929 53


1 2 Next >>