Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recruitment to activated tyrosine kinase growth factor receptors of Grb2 and p21(ras) leads to downstream activation of the kinases Raf, MAPK/Erk kinase (Mek) and, subsequently, extracellular signal-regulated kinase (Erk). Activated Erk phosphorylates specific serine residues within cytosolic phospholipase A(2) (PLA(2)), promoting enzyme translocation to membranes and facilitating liberation of arachidonic acid (AA). In the A549 human adenocarcinoma cell line dexamethasone inhibited epidermal growth factor (EGF)-stimulated cytosolic PLA(2) (cPLA(2)) activation and AA release by blocking the recruitment of Grb2 to the activated EGF receptor (EGF-R) through a glucocorticoid receptor (GR)-dependent (RU486-sensitive), transcription-independent (actinomycin-insensitive), mechanism. The dexamethasone-induced block of Grb2 recruitment was parallelled by changes in phosphorylation status and subcellular localization of lipocortin 1 (LC1) and an increase in the amount of the tyrosine phosphoprotein co-localized with EGF-R. Like dexamethasone, peptides containing E-Q-E-Y-V from the N-terminal domain of LC1 also blocked ligand-induced association of Grb2, p21(ras) and Raf. Our results point to an unsuspected rapid effect of glucocorticoids, mediated by occupation of GR but not by changes in gene transcription, which is brought about by competition between LC1 and Grb2 leading to a failure of recruitment off signalling factors to EGF-R
 ...
PMID:Glucocorticoids act within minutes to inhibit recruitment of signalling factors to activated EGF receptors through a receptor-dependent, transcription-independent mechanism. 1080 65

A phospholipase A(2) was isolated from the snake venom of Chinese Agkistrodon blomhoffii Ussurensis by column chromatography using DEAE Sephadex A-50 ion-exchange chromatography, Sephadex G-75 gel filtration chromatography and Mono Q ion-exchange chromatography, and designated as Akbu-PLA(2). It showed an average molecular mass of 13,980+/-3 amu determined by MALDI TOF mass spectrometry. Protein identification results from HPLC-nESI-MS/MS analysis indicated that the Akbu-PLA(2) was a new snake venom acidic PLA(2). Seven peptides were sequenced from Akbu-PLA(2) by HPLC-nESI-MS/MS analysis. Sequencing alignment indicated that Akbu-PLA(2) shared homolog peptides of phospholipases A(2) from the venoms of Gloydius ussurensis, Gloydius halys, Gloydius halys (halys viper), Deinagkistrodon acutus and Agkistrodon halys Pallas. Akbu-PLA(2) has an optimum hydrolytic activity temperature of approximately 45 degrees C. The intrinsic fluorescences of Tyr and Trp residues of Akbu-PLA(2) showed emission wavelengths red-shifted by 13.6 and 1.6 nm from those of free Tyr and Trp, respectively. Akbu-PLA(2) was shown to contain one Ca(2+) per monomer by ICP-AES measurement. The Ca(2+) ion was found to be critical for both the hydrolytic activity and the structure of Akbu-PLA(2). Ca(2+) increased the emission fluorescence intensity and the hydrophobicity of the environment of Akbu-PLA(2). The hydrolytic activity of Akbu-PLA(2) was accelerated due to the addition of Ca(2+) ion by enhancing the substrate binding. However, a protein component with the molecular weight two-fold relative to that of Akbu-PLA(2) was found to be difficult to eliminate for the purification of Akbu-PLA(2). HPLC-nESI-MS/MS detected the same peptides from it as from Abku-PLA(2), which indicated that it should be a homodimer of Akbu-PLA(2). A proteomic approach, 2D SDS-PAGE coupled to HPLC-nESI-MS/MS, supported the co-existence of the Akbu-PLA(2) monomer and dimer in the crude snake venom. Results from the combination of phosphoprotein and glycoprotein specific stains combined with the HPLC-nESI-MS/MS method indicated that both the Akbu-PLA(2) monomer and dimer were both phosphorylated and glycosylated. The addition of exogenous Ca(2+) ion was found to be able to promote the dimer formation of Akbu-PLA(2). We conclude that a novel PLA(2) was successfully obtained. The systemically biochemical, proteomic, structural and functional characterization results from Akbu-PLA(2) reveal new threads and provide valuable inputs for the study of snake venom phospholipases A(2).
 ...
PMID:A novel phospholipase A2 from Agkistrodon blomhoffii ussurensis venom: purification, proteomic, functional and structural characterizations. 1927 23

Results from high-performance liquid chromatography/nano-electrospray ionization tandem mass spectrometry (HPLC/nESI-MS/MS) coupled to two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D SDS-PAGE) indicated that the monomer and dimer of phospholipase A(2) (PLA(2)) coexisted in crude Chinese Agkistrodon blomhoffii Ussurensis snake venom (ABUSV). Then, an acidic PLA(2) with the accurate molecular mass of 13979.6 Da was purified from ABUSV (mo-ABUSV-aPLA(2)). MS/MS-derived peptides from ABUSV-aPLA(2) were compared with other homologous snake venom PLA(2)s, which in turn showed that ABUSV-aPLA(2) is a novel snake venom PLA(2). Meanwhile, the ABUSV-aPLA(2) dimer (di-ABUSV-aPLA(2)) was also obtained. MS/MS analysis identified the same peptides from di-ABUSV-aPLA(2) as from mo-ABUSV-aPLA(2), which indicates that di-ABUSV-aPLA(2) is a homodimer. One Ca(2+) ion is contained per ABUSV-aPLA(2). The Ca(2+) ion is critical for both the hydrolytic activity and the structure of ABUSV-aPLA(2). Pro-Q Emerald and Pro-Q Diamond specific glycoprotein and phosphoprotein staining combined with MS/MS analysis indicated that the ABUSV-aPLA(2) is both a glycoprotein and a phosphoprotein, which to our knowledge is the first such report for a snake venom PLA(2) and thus provides new threads for the study of the functions and structures of snake venom PLA(2)s. One phosphorylation site and the size of the glycan chain are determined by using HPLC/nESI-MS/MS and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS. The delicate utilization of ESI-MS can exert tremendous impact on protein sciences.
 ...
PMID:Electrospray ionization mass spectrometry as a critical tool for revealing new properties of snake venom phospholipase A2. 1928 85