Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have used the Src homology 3 (SH3) domain to screen two phage-displayed random peptide libraries, each containing 2 x 10(8) unique members, and have identified a series of high affinity peptide ligands. The peptides possess similar proline-rich regions, which yield a consensus Src SH3-binding motif of RPLPPLP. We have confirmed this motif by screening a phage-displayed peptide library biased for SH3 ligands and identifying the same consensus sequence. Binding studies using synthetic peptides suggest that the RPLPPLP motif is important for SH3 binding and confers specificity for the Src SH3 domain, and that residues which flank the motif may also contribute to binding. Peptides that contain the RPLPPLP motif compete Src, but not Abl or phospholipase C gamma, SH3 interactions with SH3-binding proteins from cell lysates (IC50 = 1-5 microM). Furthermore, RPLPPLP-related peptides are able to accelerate progesterone-induced maturation of Xenopus laevis oocytes. A similar acceleration has been observed in oocytes treated with activated, but not normal, Xenopus Src, suggesting the possibility that the peptides are able to antagonize the negative regulation of Src activity by Src SH3 in vivo.
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PMID:Identification and characterization of Src SH3 ligands from phage-displayed random peptide libraries. 792 27

A short, proline-rich region spanning residues 566-577 in human 5-lipoxygenase is a binding site for the Src homology 3 (SH3) domain of growth factor receptor-bound protein 2 (Grb2), an "adaptor" protein for tyrosine kinase-mediated cell signaling. Purified 5-lipoxygenase bound to glutathione S-transferase fusion products of Grb2 and a truncated version of Grb2 containing its SH3 domain. A peptide corresponding to the proline-rich, SH3-binding motif inhibited formation of the 5-lipoxygenase.Grb2 complex in vitro. The peptide also inhibited the redistribution of 5-lipoxygenase from the cytosol to the membrane in intact or permeabilized neutrophils activated by calcium ionophore A23187. 5-Lipoxygenase did not bind to the SH3 domains of other signaling proteins, such as GTPase-activating protein and phospholipase C gamma; however, it bound to certain cytoskeletal proteins including alpha-actinin and actin. 5-Lipoxygenase contains a consensus guanine nucleotide-binding site at residues 296-299, and guanine nucleotides inhibit 5-lipoxygenase activity in vitro. Our results suggest that 5-lipoxygenase may have a previously unrecognized role in tyrosine kinase signaling, distinct from its catalysis of lipid mediator formation. Our results also clarify the molecular basis for compartmentalization and translocation of 5-lipoxygenase in myeloid cells, implying that it binds to proteins other than its activating protein.
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PMID:5-Lipoxygenase contains a functional Src homology 3-binding motif that interacts with the Src homology 3 domain of Grb2 and cytoskeletal proteins. 792 73

Src homology 3 (SH3) domains are found in a variety of proteins that are involved in signal transduction or represent components of the cytoskeleton. These domains are thought to serve as modules that mediate specific protein-protein interactions that include proline-rich sequences on the target protein. We have identified proteins of 110, 80, 65, and 43 kDa in human embryonic fibroblasts that bind specifically to the SH3 domain of phospholipase C gamma, a primary substrate of receptor tyrosine kinases, and characterized the 110-kDa band as the microtubule-activated GTPase dynamin. In addition, dynamin binds the son of sevenless adaptor protein GRB-2 with even higher affinity. This interaction does not require the dynamin GTPase function and involves a proline-rich target sequence between residues 812 and 820 of dynamin.
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PMID:Dynamin binds to SH3 domains of phospholipase C gamma and GRB-2. 820 97

Trypanosoma brucei cDNA libraries constructed in the vector pCDM8 were screened selectively for insect (procyclic) stage surface antigen cDNAs by transient expression in mammalian COS-7 fibroblasts and "panning" with a rabbit polyclonal antiserum. This strategy yielded two surface antigen cDNAs termed PSSA-1 and PSSA-2. The PSSA-1 cDNA encoded an isotype of procyclin, the major phosphatidylinositol-linked stage-specific glycoprotein antigen of the tsetse fly infective forms of T. brucei. The PSSA-2 cDNA encoded a new and previously unidentified stage-specific surface antigen with the features of a typical transmembrane glycoprotein but with an unusual cytoplasmic tail composed of a proline-rich tandem repeat. Fluorescent antibody staining of PSSA-1 transfected COS cells with a panel of procyclin-specific monoclonal antibodies confirmed that the protein was located on the outer surface of the plasma membrane. Furthermore, the antigen on COS cells was insensitive to treatment with phosphatidylinositol-specific phospholipase C suggesting that the inositol of the glycosylinositol phospholipid-lipid anchor contained the same fatty acyl modification reported recently for the procyclin molecule in cultured procyclic trypanosomes. In contrast the PSSA-2 antigen on COS cells was stained very weakly by whole parasite antisera. Northern blot hybridization revealed that the PSSA-2 antigen was encoded by a single 1.7-kilobase transcript which was present in parasites from the insect procyclic stage of the life cycle but not from the animal bloodstream stage. Southern blot hybridization analysis of DNA from procyclic stage trypanosomes indicated that the gene for PSSA-2 may be present in more than one copy in procyclic trypanosomes.
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PMID:Cloning of a novel surface antigen from the insect stages of Trypanosoma brucei by expression in COS cells. 842 Sep 63

Scr homology 3 (SH3) domain-mediated protein-protein interactions have been implicated in the localization of proteins to specific sites within the cell. We present evidence that the product of the vav proto-oncogene, p95vav, interacts specifically with the focal adhesion protein zyxin both in vitro and in yeast two hybrid system. Solution binding and two-hybrid system experiments demonstrate that association of Vav with the LIM domain protein zyxin is mediated by the C-terminal SH3 domain of the Vav and involves the proline-rich N-terminus of zyxin. The interaction appears to be selective, since no binding of the proline-rich N-terminus of zyxin with other SH3 domain-containing proteins such as GRB-2, phospholipase C gamma, GTPase-activating protein, or p85 was detected.
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PMID:SH3 domain-dependent interaction of the proto-oncogene product Vav with the focal contact protein zyxin. 862 75

We present characterization of the rhodopsin, Gq and phosphatidylinositol-specific phospholipase C (PLC) from the signal transduction pathway of cephalopod photoreceptors. Cephalopod rhodopsins are unique in possessing a C-terminal extension of proline-rich repeats, and they have a strong tendency to form ordered arrays. Two-dimensional arrays of a full-length and C-terminally-truncated cephalopod rhodopsin have been obtained. The C termini appear to cluster the rhodopsins into small groups. An AlF4(-)-activated Gq alpha subunit has been isolated and shown to activate a partially purified PLC beta. This 130 kDa PLC, isolated by absorption on heparin agarose, showed a specific activity of 195 nmol of phosphatidylinositol 4,5-bisphosphate hydrolysed per milligram of protein per minute in the presence of 1.6 microM free calcium.
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PMID:Rhodopsin, Gq and phospholipase C activation in cephalopod photoreceptors. 882 31

The formation of cell membrane following CSF-1 stimulation of a macrophage cell line is coordinated with cell cycle progression. The majority of membrane phospholipid accumulates during the S phase and results from cell-cycle dependent oscillations in the rates of phosphatidylcholine biosynthesis and degradation. Both synthesis and degradation are enhanced during the G1 phase, resulting in a high rate of phosphatidylcholine turnover. Degradation of phosphatidylcholine after CSF-1 stimulation is mediated by a phospholipase C, and the release of diacylglycerol during G1 phase is biphasic. The degradation essentially stops during the S phase, thus allowing biosynthesis to supply the necessary membrane for cell division and doubling. The degradation of phosphatidylcholine during G1 signals the downstream activation of c-fos and junB transcription and can be mimicked by incubation of the macrophage cells with exogenous bacterial phospholipase C. In contrast, the expression of c-myc transcripts normally associated with CSF-1 stimulation is severely compromised in phospholipase C-treated cells, indicating that the diacylglycerol signals a pathway distinct from the pathway that governs c-myc activation. Constitutive expression of c-myc complements phospholipase C activity and permits the growth of cells in the presence of exogenous bacterial enzyme and the absence of CSF-1. Protein kinase C is not required to mediate the diacylglycerol signal that supports cell growth. GTP exchange on Ras is not enhanced, and MAP kinase activity is not stimulated in response to phosphatidylcholine degradation by exogenous phospholipase C. The 85 kDa cytoplasmic phospholipase A2 is activated, however, as well as a novel protein we have called p96. Rapid serine phosphorylation of p96 follows stimulation of cells with either CSF-1 or exogenous phospholipase C. Analysis of the murine cDNA encoding p96 reveals an amino-terminal domain with significant similarity to the amino-terminal domain of the Drosophila-disabled gene product and a carboxy-terminal domain containing proline-rich sequences characteristic of SH3 binding regions. The sequence of p96 suggests an interactive role for this unique protein in the CSF-1 signal transduction cascade.
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PMID:Phosphatidylcholine signaling in response to CSF-1. 898 60

An aminopeptidase N (APN) with a molecular weight of 110kDa was released from the midgut membrane of Bombyx mori by phosphatidylinositol-specific phospholipase C (PI-PLC), and purified to a homogeneous state. This 110-kDa APN was different from the 100-kDa APN that we previously reported, in chromatographic behaviors, substrate specificity, and N-terminal and internal amino acid sequences. However, the N-terminal sequence of 110-kDa APN, DPAFRLPTTTRPRHYQVTLT, was highly homologous with those of Manduca sexta and Heliothis virescens APNs, which were identified as a receptor for an insecticidal toxin of Bacillus thuringiensis. From a B. mori midgut cDNA library, we cloned the 110-kDa APN cDNA that possessed a 2958-bp open reading frame encoding a 111573-Da polypeptide of 986 residues. The sequence of the eicosa-peptide Asp42Thr61 deduced from the cDNA was completely matched with the N-terminal sequence of the mature 110-kDa APN. One potential N-glycosylation site, HEXXHXW zinc-binding motif and characteristic proline-rich repeats were observed in the ORF. Moreover, the primary sequence contained two hydrophobic peptides on N- and C-termini. The N-terminal peptide sequence showed characteristics of leader peptide for secretion and the C-terminal peptide contained a possible glycosylphosphatidylinositol (GPI) anchoring site. Taken together, the deduced amino acid sequence suggests that the 110-kDa APN is a GPI-anchored protein and a specific receptor protein for B. thuringiensis CryIA delta-endotoxin.
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PMID:Molecular cloning of a GPI-anchored aminopeptidase N from Bombyx mori midgut: a putative receptor for Bacillus thuringiensis CryIA toxin. 972 21

Sam68 is a 68 kDa protein that associates with and is phosphorylated by the c-Src kinase at mitosis. It contains a KH domain implicated in RNA binding and several proline-rich motifs that resemble known SH3 binding sites. The SH3 domains of c-Src, phosphatidylinositol 3-OH kinase, phospholipase C-gamma and Grb2 protein (containing two SH3 domains), but not other SH3 domains tested, were capable of binding Sam68 in vitro. Synthetic peptides corresponding to the proline motifs of Sam68 inhibited with different efficiencies the binding of SH3 domains to Sam68 suggesting that the proline motifs of Sam68 function as specific SH3 domain binding sites. Mutation of Sam68 SH3 binding sites further indicated that the SRC SH3 domain mediates binding of Src to unphosphorylated Sam68. Phosphorylation of Sam68 by Src kinase was inhibited when the Src SH3 binding site of Sam68 was mutated or when corresponding peptides were added to in vitro kinase reactions indicating that binding of the Src SH3 domain to a specific site near the amino-terminus of Sam68 (including residues 38 - 45: PPLPHRSR) facilitates phosphorylation of Sam68 by the Src kinase domain. Sam68-based proline peptides had no effect on the phosphorylation of another in vitro substrate of Src, enolase. These results suggest that Src effectively mounts Sam68 through its SH3 domain, possibly as a mechanism to position the kinase domain close to substrate tyrosine residues in the carboxyl-half of the protein.
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PMID:Evidence for SH3 domain directed binding and phosphorylation of Sam68 by Src. 1046 11

The COOH-terminal domain of the NR2D subunit of the NMDA receptor contains proline-rich regions that show striking homology to sequences known to bind to Src homology 3 (SH3) domains. To determine whether the proline-rich region of the NR2D subunit interacts with specific SH3 domains, in vitro SH3 domain binding assays were performed. A proline-rich fragment of the NR2D subunit (2D(866-1064)) bound to the Abl SH3 domain but not to the SH3 domains from Src, Fyn, Grb2, GAP, or phospholipase C-gamma (PLCgamma). Co-immunoprecipitation of NR2D with Abl suggests stable association of NR2D and Abl in transfected cells. The SH3 domain plays an important role in the negative regulation of Abl kinase activity. To determine whether the interaction of NR2D with the Abl SH3 domain alters Abl kinase activity, Abl was expressed alone or with NR2D in 293T cells. Autophosphorylation of Abl was readily observed when Abl was expressed alone. However, co-expression of Abl with 2D(866-1064) or full-length NR2D inhibited autophosphorylation. 2D(866-1064) did not inhibit DeltaSH3 Abl, indicating a requirement for the Abl SH3 domain in the inhibitory effect. Similarly, 2D(866-1064) did not inhibit the catalytic activity of Abl-PP, which contains two point mutations in the SH2-kinase linker domain that release the negative kinase regulation by the SH3 domain. In contrast, the full-length NR2D subunit partially inhibited the autokinase activity of both DeltaSH3 Abl and Abl-PP, suggesting that NR2D and Abl may interact at multiple sites. Taken together, the data in this report provide the first evidence for a novel inhibitory interaction between the NR2D subunit of the NMDA receptor and the Abl tyrosine kinase.
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PMID:Interaction of the N-methyl-D-aspartic acid receptor NR2D subunit with the c-Abl tyrosine kinase. 1077 67


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