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P Douglas

Publications and source records attributed to P Douglas.

At least 19 recordsLinked to original sources
PubMed2006

Controlling the color space response of colorimetric luminescent oxygen sensors.

The color space response of colorimetric luminescent oxygen sensors is described in terms of the Commission Internationale de l'Eclairage (CIE) x,y color coordinates. We show how the color change response to oxygen can be obtained, provided the quenching kinetics for all lumophores involved can be represented mathematically. The theory is illustrated by analysis of examples of theoretical sensors in which lumophores are quenched by Stern-Volmer kinetics to give red to green, green to red, and red to green to blue color responses as the partial pressure of oxygen is increased. The effects of lumophore emission lifetime and the permeability of the polymer matrix to oxygen are discussed in terms of the control of sensor response, which variations in these parameters offer.

Journal Article↗
PubMed2006

Tunable Tsallis distributions in dissipative optical lattices.

We demonstrated experimentally that the momentum distribution of cold atoms in dissipative optical lattices is a Tsallis distribution. The parameters of the distribution can be continuously varied by changing the parameters of the optical potential. In particular, by changing the depth of the optical lattice, it is possible to change the momentum distribution from Gaussian, at deep potentials, to a power-law tail distribution at shallow optical potentials.

Journal Article↗
PubMed2006

Filtration, haze and foam characteristics of fermented wort mediated by yeast strain.

AIMS: To investigate the influence of the choice of yeast strain on the haze, shelf life, filterability and foam quality characteristics of fermented products. METHODS AND RESULTS: Twelve strains were used to ferment a chemically defined wort and hopped ale or stout wort. Fermented products were assessed for foam using the Rudin apparatus, and filterability and haze characteristics using the European Brewing Convention methods, to reveal differences in these parameters as a consequence of the choice of yeast strain and growth medium. CONCLUSIONS: Under the conditions used, the choice of strain of Saccharomyces cerevisiae effecting the primary fermentation has an impact on all of the parameters investigated, most notably when the fermentation medium is devoid of macromolecular material. SIGNIFICANCE AND IMPACT OF THE STUDY: The filtration of fermented products has a large cost implication for many brewers and wine makers, and the haze of the resulting filtrate is a key quality criterion. Also of importance to the quality of beer and some wines is the foaming and head retention of these beverages. The foam characteristics, filterability and potential for haze formation in a fermented product have long been known to be dependant on the raw materials used, as well as other production parameters. The choice of Saccharomyces cerevisiae strain used to ferment has itself been shown here to influence these parameters.

Beer↗
PubMed2005

Resonant activation in a nonadiabatically driven optical lattice.

We demonstrate the phenomenon of resonant activation in a nonadiabatically driven dissipative optical lattice with broken time symmetry. The resonant activation results in a resonance as a function of the driving frequency in the current of atoms through the periodic potential. We demonstrate that the resonance is produced by the interplay between deterministic driving and fluctuations, and we also show that by changing the frequency of the driving it is possible to control the direction of the diffusion.

Journal Article↗
PubMed2001

Invasive bladder carcinoma: a pilot study of conservative treatment with accelerated radiotherapy and concomitant cisplatin.

From November 1992 to December 1997, 25 patients (inoperable or refusing cystectomy) were included in a prospective study to assess the feasibility, tolerance, and curative potential of accelerated radiotherapy (RT) and concomitant cisplatin. Median age was 74 years (range 49-86). Stage distribution was as follows: 1 T1, 10 T2, 8 T3, and 6 T4. Two patients had clinically positive pelvic nodes. The goal was to deliver a total dose of 40 Gy to the whole pelvis and bladder in 4 weeks using a concomitant boost of 20 Gy to the tumor or to the whole bladder during the third and fourth weeks (total dose 60 Gy), with daily cisplatin (6 mg/m(2)) before RT for patients with creatinine clearance > 50 ml/min. All but one patient completed the RT protocol. Daily cisplatin was successfully delivered in 18 patients. One patient presented with grade III ototoxicity. Diarrhea was scored grade III in two and grade IV in two patients. Acute urinary toxicity was scored grade III in one patient. Posttreatment late effects included bladder grade II and grade III in two patients and one patient, respectively; large bowel grade III in one; urethral grade III in one; and femoral head radionecrosis in one. Four-year overall and disease-specific survival rates were 23% and 35%, respectively. The latter was 60% for patients with T2 tumors. The 4-year actuarial locoregional control rate for all patients was 61%. In summary, accelerated RT and concomitant cisplatin is feasible with acceptable tolerance even in relatively old patients. Although outcome was better for patients with low-stage tumors, local control and survival rates appeared similar to those of standard RT schedules for a similar patient population.

Aged↗
PubMed2001

Protein phosphatases regulate DNA-dependent protein kinase activity.

DNA-dependent protein kinase (DNA-PK) is a complex of DNA-PK catalytic subunit (DNA-PKcs) and the DNA end-binding Ku70/Ku80 heterodimer. DNA-PK is required for DNA double strand break repair by the process of nonhomologous end joining. Nonhomologous end joining is a major mechanism for the repair of DNA double strand breaks in mammalian cells. As such, DNA-PK plays essential roles in the cellular response to ionizing radiation and in V(D)J recombination. In vitro, DNA-PK undergoes phosphorylation of all three protein subunits (DNA-PK catalytic subunit, Ku70 and Ku80) and phosphorylation correlates with inactivation of the serine/threonine protein kinase activity of DNA-PK. Here we show that phosphorylation-induced loss of the protein kinase activity of DNA-PK is restored by the addition of the purified catalytic subunit of either protein phosphatase 1 or protein phosphatase 2A (PP2A) and that this reactivation is blocked by the potent protein phosphatase inhibitor, microcystin. We also show that treating human lymphoblastoid cells with either okadaic acid or fostriecin, at PP2A-selective concentrations, causes a 50-60% decrease in DNA-PK protein kinase activity, although the protein phosphatase 1 activity in these cells was unaffected. In vivo phosphorylation of DNA-PKcs, Ku70, and Ku80 was observed when cells were labeled with [(32)P]inorganic phosphate in the presence of the protein phosphatase inhibitor, okadaic acid. Together, our data suggest that reversible protein phosphorylation is an important mechanism for the regulation of DNA-PK protein kinase activity and that the protein phosphatase responsible for reactivation in vivo is a PP2A-like enzyme.

Alkenes↗
PubMed2001

Efficacy of intracoronary or intravenous VEGF165 in a pig model of chronic myocardial ischemia.

OBJECTIVES: We sought to optimize vascular endothelial growth factor (VEGF) treatment for therapeutic angiogenesis in myocardial ischemia, we explored the efficacy of five different regimens. BACKGROUND: Although VEGF165 is one of the most potent pro-angiogenic growth factors, VEGF165 treatment for myocardial ischemia has been hampered by low efficacy and dose-limiting hypotension after systemic or intracoronary delivery. METHODS: This study evaluated the effect of intravenous or intracoronary rhVEGF165 in the presence or absence of nitric oxide (NO) synthase inhibition in a porcine model of chronic myocardial ischemia. Forty-two Yorkshire pigs with chronically occluded left circumflex coronary arteries were randomly assigned to receive 10 microg/kg of VEGF165: 1) rapid (40 min) intravenous VEGF165 0.25 microg/kg/min, 2) slow (200 min) intravenous VEGF165 0.05 microg/kg/min, 3) rapid intracoronary VEGF165 0.25 microg/kg/min, 4) rapid intracoronary VEGF165 0.25 microg/kg/min + nitro-L-arginine methyl ester hydrochloride (L-NAME) or 5) rapid vehicle infusion. RESULTS: Intracoronary and intravenous VEGF165 induced hypotension. Intracoronary VEGF-induced hypotension was blocked by L-NAME. Coronary angiography three weeks after treatment showed improvement in collateral index in both intracoronary groups but not the intravenous VEGF165 groups. Likewise, myocardial blood flow and microvascular function in the ischemic territory improved in both intracoronary groups but not in the intravenous groups. Global and regional myocardial function showed no significant improvements in any groups. CONCLUSIONS: Intracoronary infusion of VEGF165 significantly improves blood flow to the ischemic myocardium. Concomitant administration of L-NAME inhibits VEGF-induced hypotension while most likely preserving VEGF-induced angiogenesis. Intravenous infusion of VEGF165 was not effective in augmenting either myocardial flow or function in this model.

Animals↗
PubMed2001

Radiation therapy alone or combined surgery and radiation therapy in squamous-cell carcinoma of the penis?

To assess the prognostic factors and the outcome in patients with squamous-cell carcinoma of the penis, a retrospective review of 41 consecutive patients with non-metastatic invasive carcinoma of the penis, treated between 1962 and 1994, was performed. The median age was 59 years (range: 35-76 years). According to the International Union Against Cancer (UICC) 1997 classification, there were 12 (29%) T1, 24 (59%) T2, 4 (10%) T3 and 1 TX (2%) tumours. The N-classification was distributed as follows: 29 (71%) patients with N0, 8 (20%) with N1, 3 (7%) with N2 and 1 (2%) with N3. Forty-four per cent (n=18) of the patients underwent surgery: partial penectomy with (n=4) or without (n=12) lymph node dissection, or total penectomy with (n=1) or without (n=1) lymph node dissection. 23 patients were treated with radiation therapy alone, and all but 4 of the patients who were operated upon received postoperative radiation therapy (n=14). The median follow-up period was 70 months (range 20-331 months). In a median period of 12 months (range 5-139 months), 63% (n=26) of the patients relapsed (local in 18, locoregional in 2, regional in 3 and distant in 3). Local failure (stump in the operated patients, and the tumour bed in those treated with primary radiation therapy) was observed in 4 out of 16 (25%) patients treated with partial penectomy +/-postoperative radiotherapy versus 14 out of 23 (61%) treated with primary radiotherapy (P=0.06). 15 (83%) out of 18 local failures were successfully salvaged with surgery. In all patients, 5- and 10-year survival rates were 57% (95% confidence interval (CI), 41-73%) and 38% (95% CI, 21-55%), respectively. The 5-year local and locoregional rates were 57% (95% CI, 41-73%) and 48% (95% CI, 32-64%), respectively. In patients treated with primary radiotherapy, 5- and 10-year probabilities of surviving with penis preservation were 36% (95% CI, 22-50%) and 18% (95% CI, 2-34%), respectively. In multivariate analyses, survival was significantly influenced by the N-classification, and surgery was the only independent factor predicting the locoregional control. We conclude that, in patients with squamous-cell carcinoma of the penis, local control is better in patients treated with surgery. However, there seems to be no difference in terms of survival between patients treated by surgery and those treated by primary radiotherapy +/-salvage surgery, with 39% having organ preservation.

Adult↗
PubMed2001

Prevention of orthopaedic wound infections: a quality improvement project.

Using clinical practice improvement methodology, a project was undertaken to reduce the incidence of surgical wound infections following elective hip and knee replacement surgery. A team was established, key measures for improvement were identified, strategies for change were developed and an action plan was implemented. Outcomes for this project included a reduction in the rate of clean surgical wound infection for joint replacement surgery from 28% to zero. Average length of stay for total hip replacement surgery was reduced from 13.9 to 9.3 days and from 14.6 to 10.4 days for total knee replacement surgery. Guidelines for patient selection were developed along with a protocol for the management of preparation to prevent urinary tract infections. Post-discharge surveillance and a preoperative rehabilitation and exercise programme have been implemented. There is potential for wider uptake and implementation of the quality principles described herein.

Arthroplasty, Replacement, Hip↗
PubMed2001

Transesophageal echocardiographic evaluation of native aortic valve area: utility of the double-envelope technique.

OBJECTIVE: To assess the accuracy of aortic valve area (AVA) calculations using the continuity equation with data obtained from the double envelope (DE) (simultaneously obtained left ventricular outflow tract [V1]) and aortic valve [V2] velocities) during intraoperative transesophageal echocardiography (TEE). DESIGN: Prospective study; measurements were performed on-line. SETTING: University hospital. PARTICIPANTS: Cardiac and noncardiac surgical patients (n = 75) with recent aortic valve assessment (<3 months) undergoing general anesthesia or endotracheal intubation. INTERVENTIONS: Intraoperative AVA was measured by the continuity equation using the DE technique (DE/TEE) and by planimetry (PL/TEE). Left ventricular outflow tract diameter was obtained from midesophageal views, whereas subvalvular (V1) and valvular (V2) velocities were obtained simultaneously using continuous-wave Doppler from transgastric views. V1 was also obtained using pulsed-wave Doppler. Measurements were compared with AVA obtained preoperatively by the Gorlin equation during cardiac catheterization (G/CATH) or by transthoracic echocardiography using the traditional continuity equation (C/TTE) (nonsimultaneously obtained V1 and V2). MEASUREMENTS AND MAIN RESULTS: A DE was obtained in 73 of 75 patients (97%). Four patients had atrial fibrillation at the time of the examination, whereas the rest were in sinus rhythm. PL/TEE was performed in 54 of 71 patients with sinus rhythm (76%). Agreement was good between DE/TEE and G/CATH (mean bias, 0.02 cm(2) [SD, 0.24 cm(2)]), and C/TTE (mean bias, -0.05 cm(2) [SD, 0.16 cm(2)]). Agreement was not as good between PL/TEE and G/CATH (mean bias, -0.07 cm(2) [SD, 0.28 cm(2)]) and C/TTE (mean bias, -0.13 cm(2) [SD, 0.30 cm(2)]). V1 obtained by pulsed-wave Doppler and with DE closely agreed (mean bias, 0.01 m/sec [SD, 0.05 m/sec]). CONCLUSION: TEE evaluation of native AVA using the DE technique is feasible and in good agreement with that obtained by C/TTE and G/CATH. Compared with DE/TEE, PL/TEE did not agree as well. Use of DE/TEE should simplify the continuity equation and may minimize errors resulting from beat-to-beat variability in stroke volume.

Aged↗
PubMed2000

Purification and characterization of ATM from human placenta. A manganese-dependent, wortmannin-sensitive serine/threonine protein kinase.

ATM is mutated in the human genetic disorder ataxia telangiectasia, which is characterized by ataxia, immune defects, and cancer predisposition. Cells that lack ATM exhibit delayed up-regulation of p53 in response to ionizing radiation. Serine 15 of p53 is phosphorylated in vivo in response to ionizing radiation, and antibodies to ATM immunoprecipitate a protein kinase activity that, in the presence of manganese, phosphorylates p53 at serine 15. Immunoprecipitates of ATM also phosphorylate PHAS-I in a manganese-dependent manner. Here we have purified ATM from human cells using nine chromatographic steps. Highly purified ATM phosphorylated PHAS-I, the 32-kDa subunit of RPA, serine 15 of p53, and Chk2 in vitro. The majority of the ATM phosphorylation sites in Chk2 were located in the amino-terminal 57 amino acids. In each case, phosphorylation was strictly dependent on manganese. ATM protein kinase activity was inhibited by wortmannin with an IC(50) of approximately 100 nM. Phosphorylation of RPA, but not p53, Chk2, or PHAS-I, was stimulated by DNA. The related protein, DNA-dependent protein kinase catalytic subunit, also phosphorylated PHAS-I, RPA, and Chk2 in the presence of manganese, suggesting that the requirement for manganese is a characteristic of this class of enzyme.

Androstadienes↗
PubMed2000

Multidisciplinary Women's health research: the national centers of excellence in women's health.

Contemporary research increasingly needs to consider the value of a multidisciplinary approach in answering critical health questions. The current article outlines the need for multidisciplinary investigations specifically in reference to women's health, and addresses issues related to generating and sustaining interest in such an approach. In addition, the importance of resources and environment for facilitating multidisciplinary research and advocacy efforts for obtaining funding for this approach are discussed. Methodological issues pertinent to the operationalization of multidisciplinary research in women's health are also addressed, and lessons learned from the National Centers of Excellence in initiating multidisciplinary research in women's health are reviewed.

Female↗
PubMed2000

An evaluation of prosthetic aortic valves using transesophageal echocardiography: the double-envelope technique.

UNLABELLED: The conventional continuity equation uses nonsimultaneous measurements of blood flow velocities through the left ventricular outflow tract and across the aortic valve to calculate aortic valve area (AVA). We have noted that both velocities can be simultaneously obtained from continuous wave (CW) Doppler analysis (double-envelope [DE]). We hypothesize that prosthetic AVA can be calculated by using the DE technique, during transesophageal echocardiography (TEE). Prosthetic AVA was calculated in 41 of 45 patients immediately after aortic valve replacement by using the DE/AVA technique. Left ventricular outflow tract diameter was obtained from an esophageal view, while subvalvular (V(1)) and valvular (V(2)) peak velocities were simultaneously obtained from transgastric views by using CW Doppler. Prosthetic AVA and V(1)/V(2) ratio (Doppler velocity index) were calculated. V(1) was also measured by using pulse wave Doppler, as is conventionally done. Twenty-three Carbomedic (CM) and 18 Carpentier-Edwards (CE) AVA were evaluated. DE/AVAs for CM and CE valves correlated and agreed with that reported by the manufacturer (CM r(2) = 0.91, mean bias -0.25 cm(2) [SD 0.18]; CE r(2) = 0.73, mean bias -0.02 cm(2) [SD 0.27]). Calculated Doppler velocity index values agree with available data (mean bias 0.03 [SD 0.05]). The V(1) obtained by using the DE method was nearly identical to the V(1) obtained by using pulse wave (r(2) = 0.95, mean bias 0.02 m/s [SD 0.04 m/s]). TEE assessment of prosthetic AVA using the DE technique agrees with data reported by the manufacturer. Obtaining subvalvular and valvular velocities from the same CW Doppler trace may simplify the continuity equation and help avoid errors caused by beat-to-beat changes in blood flow. Quantitative prosthetic aortic valve assessment can be performed, on-line, with TEE by using the DE technique. IMPLICATIONS: Quantitative assessment of prosthetic aortic valve area can be performed on-line by using transesophageal echocardiography using the double envelope technique.

Algorithms↗
PubMed1999

Phosphorylation-dependent interactions between enzymes of plant metabolism and 14-3-3 proteins.

Far-Western overlays of soluble extracts of cauliflower revealed many proteins that bound to digoxygenin (DIG)-labelled 14-3-3 proteins. Binding to DIG-14-3-3s was prevented by prior dephosphorylation of the extract proteins or by competition with 14-3-3-binding phosphopeptides, indicating that the 14-3-3 proteins bind to phosphorylated sites. The proteins that bound to the DIG-14-3-3s were also immunoprecipitated from extracts with anti-14-3-3 antibodies, demonstrating that they were bound to endogenous plant 14-3-3 proteins. 14-3-3-binding proteins were purified from cauliflower extracts, in sufficient quantity for amino acid sequence analysis, by affinity chromatography on immobilised 14-3-3 proteins and specific elution with a 14-3-3-binding phosphopeptide. Purified 14-3-3-binding proteins included sucrose-phosphate synthase, trehalose-6-phosphate synthase, glutamine synthetases, a protein (LIM17) that has been implicated in early floral development, an approximately 20 kDa protein whose mRNA is induced by NaCl, and a calcium-dependent protein kinase that was capable of phosphorylating and rendering nitrate reductase (NR) sensitive to inhibition by 14-3-3 proteins. In contrast to the phosphorylated NR-14-3-3 complex which is activated by dissociation with 14-3-3-binding phosphopeptides, the total sugar-phosphate synthase activity in plant extracts was inhibited by up to 40% by a 14-3-3-binding phosphopeptide and the phosphopeptide-inhibited activity was reactivated by adding excess 14-3-3 proteins. Thus, 14-3-3 proteins are implicated in regulating several aspects of primary N and C metabolism. The procedures described here will be valuable for determining how the phosphorylation and 14-3-3-binding status of defined target proteins change in response to extracellular stimuli.

14-3-3 Proteins↗
PubMed1998

Purification of a nitrate reductase kinase from Spinacea oleracea leaves, and its identification as a calmodulin-domain protein kinase.

Spinach (Spinacea oleracea L.) nitrate reductase (NR) is inactivated by phosphorylation on serine-543, followed by binding of the phosphorylated enzyme to 14-3-3 proteins. We purified one of several chromatographically distinct NRserine-543 kinases from spinach leaf extracts, and established by Edman sequencing of 80 amino acid residues that it is a calcium-dependent (calmodulin-domain) protein kinase (CDPK), with peptide sequences very similar to Arabidopsis CDPK6 (accession no. U20623; also known as CPK3). The spinach CDPK was recognized by antibodies raised against Arabidopsis CDPK. Nitrate reductase was phosphorylated at serine-543 by bacterially expressed His-tagged CDPK6, and the phosphorylated NR was inhibited by 14-3-3 proteins. However, the bacterially expressed CDPK6 had a specific activity approx. 200-fold lower than that of the purified spinach enzyme. The physiological control of NR by CDPK is discussed, and the regulatory properties of the purified CDPK are considered with reference to current models for reversible intramolecular binding of the calmodulin-like domain to the autoinhibitory junction of CDPKs.

Amino Acid Sequence↗
PubMed1997

Three spinach leaf nitrate reductase-3-hydroxy-3-methylglutaryl-CoA reductase kinases that are regulated by reversible phosphorylation and/or Ca2+ ions.

In spinach (Spinacea oleracea L.) leaf extracts, three protein kinases (PKI, PKII and PKIII) were identified each of which phosphorylated spinach nitrate reductase on serine-543, and inactivated the enzyme in the presence of nitrate reductase inhibitor, 14-3-3. PKIII was also very active in phosphorylating and inactivating Arabidopsis (Landsberg erecta) 3-hydroxy-3-methylglutaryl-coenzyme A reductase 1 (HMGR1). PKI and PKII phosphorylated HMGR1 more slowly than PKIII, compared with their relative rates of phosphorylation of nitrate reductase. HMGR1 identical with those that are seen after phosphorylation of serine-577 by the sucrose non-fermenting (SNF1)-like PK, 3-hydroxy-3-methylglutaryl-Co A reductase kinase A (HRK-A), from cauliflower [Dale, Arró, Becerra, Morrice, Boronat, Hardie and Ferrer (1995) Eur. J. Biochem. 233, 506-513]. PKI was Ca2+-dependent when prepared in the absence of protein phosphatase (PP) inhibitors, and largely Ca2+-dependent when prepared in the presence of PP inhibitors (NaF and EGTA). The Ca2+-independent portion of PKI was inactivated by either PP2A or PP2C, while the Ca2+-dependent portion of PKI became increasingly activated during storage, which we presume was mimicking the effect of an unidentified PP. These findings indicate that PK1 is regulated by two functionally distinct phosphorylations. PKI had a molecular mass of 45 kDa on gel filtration and was active towards substrate peptides that terminated at the +2 residue from the phosphorylation site, whereas PKIII was inactive towards these peptides. PKII was Ca2+-stimulated under all conditions tested. PKIII was Ca2+-indepdented, inactivated by PP2A or PP2C, had a requirement for a hydrophobic residue in the +4 position of peptide substrates, had a molecular mass by gel filtration of approximately 140 kDa, and an antibody against the rye SNF1-related PK (RKIN1) recognized a 58 kDa subunit in fractions containing PKIII. These properties of PKIII are identical with those reported previously for the SNF1-like enzyme, HRK-A. Our results indicate a considerable complexity of kinase cascades mediating the regulation of assimilatory and biosynthetic pathways in response to environmental stimuli in plants.

Amino Acid Sequence↗
PubMed1996

Phosphorylated nitrate reductase from spinach leaves is inhibited by 14-3-3 proteins and activated by fusicoccin.

BACKGROUND: Nitrate reductase (NR) in leaves is rapidly inactivated in the dark by a two-step mechanism in which phosphorylation of NR on the serine at position 543 (Ser543) promotes binding to nitrate reductase inhibitor protein (NIP). The eukaryotic 14-3-3 proteins bind to many mammalian signalling components (Raf-1, Bcr, phosphoinositide 3-kinase, protein kinase C, polyomavirus middle-T antigen and Cdc25), and are implicated in the timing of mitosis, DNA-damage checkpoint control, exocytosis, and activation of the plant plasma-membrane H+-ATPase by fusicoccin. Their dimeric, saddle-shaped structures support the proposal that 14-3-3 proteins are 'adaptors' linking different signalling proteins, but their precise functions are still a mystery. RESULTS: We purified NIP to homogeneity and established by means of amino-acid sequencing that it is a mixture of several 14-3-3 isoforms. Mammalian and yeast 14-3-3 proteins were just as effective as NIP at inhibiting phosphorylated NR. The sequence around Ser543, the phosphorylation site in NR, is strikingly similar to the sequences around the phosphoserine residues (Ser259 and Ser621) of mammalian Raf-1 that interact with 14-3-3 proteins. We found that NIP activity was blocked by a synthetic phosphopeptide corresponding to residues 251-266 of Raf. Fusicoccin also blocked NIP activity, and plant plasma-membrane H+-ATPases were activated by either fusicoccin, the phosphoserine259-Raf-1 peptide, or protein phosphatase 2A. CONCLUSIONS: Our findings establish that the mechanism of inactivation of NR involves the phosphorylation of Ser 543 followed by interaction with one or more plant 14-3-3 proteins. These results support the idea of a common mechanism for binding of 14-3-3 to its targets in all eukaryotes, and suggest that the phosphoserine259-Raf-1 peptide and fusicoccin may be of general use for disrupting the interaction of 14-3-3 with its target proteins. We propose that the plant plasma-membrane H+-ATPase is regulated in an analogous manner to NR-NIP, and speculate that 14-3-3 proteins provide a link between 'sensing' the activity state of NR and signalling to other cellular processes in plants.

14-3-3 Proteins↗