30 research outputs found
Phenylarsine oxide inhibits the fusicoccin-induced activation of plasma membrane H+-ATPase
No full textTo investigate the mechanism by which fusicoccin (FC) induces the activation of the plasma membrane (PM) H+-ATPase, we used phenylarsine oxide (PAO), a known inhibitor of protein tyrosine-phosphatases. PAO was supplied in vivo in the absence or presence of FC to radish (Raphanus sativus L.) seedlings and cultured Arabidopsis cells prior to PM extraction. Treatment with PAO alone caused a slight decrease of PM H+-ATPase activity and, in radish, a decrease of PM-associated 14-3-3 proteins. When supplied prior to FC, PAO drastically inhibited FC-induced activation of PM H+-ATPase, FC binding to the PM, and the Pc-induced increase of the amount of 14-3-3 associated with the PM. On the contrary, PAO was completely ineffective on all of the above-mentioned parameters when supplied after FC. The H+-ATPase isolated from PAO-treated Arabidopsis cells maintained the ability to respond to FC if supplied with exogenous, nonphosphorylated 14-3-3 proteins. Altogether, these results are consistent with a model in which the dephosphorylated state of tyrosine residues of a protein(s), such as 14-3-3 protein, is required to permit FC-induced association between the 14-3-3 protein and the PM H+-ATPase
PPI1, UNA NUOVA PROTEINA CAPACE DI INTERAGIRE CON IL DOMINIO C-TERMINALE DELL' H+-ATPASI DEL PLASMALEMMA
No full textIl dominio autoinibitorio C-terminale dell' H+-ATPasi del plasmalemma costituisce il principale sito di regolazione dell'enzima: la sua rimozione proteolitica, così come il legame di proteine 14-3-3 ad una sequenza contenuta in questa regione, causano un aumento dell'attività enzimatica. Utilizzando il metodo del doppio ibrido abbiamo identificato una proteina di 612 aa (Ppi1, proton pump interactor), la cui porzione N-terminale (88aa) interagisce con il dominio C-terminale dell'H+-ATPasi, isoforma AHA1. Diversi geni di Arabidopsis thaliana e alcuni EST di diverse specie vegetali mostrano una omologia di sequenza significativa (50-70% in porzioni di 200-600 aa) con Ppi1. La regione N-terminale di Ppi1 è stata espressa in E. coli come proteina di fusione con la GST o con una coda di istidine (His6-Ppi). In esperimenti di overlay, entrambe le proteine di fusione si legano all'H+-ATPasi immunoprecipitata da una frazione di plasmalemma purificata da cellule in coltura di A. thaliana His6-Ppi stimola l'attività dell'H+-ATPasi; lo stimolo è maggiore a pH 6.4 (massimo stimolo a 20 mM His-Ppi) che a pH 7.3, dove lo stimolo non è saturato neppure alla concentrazione di 60 mM. L'attivazione indotta da Ppi1 è sinergica con quella indotta da fusicoccina e da tripsina; inoltre His6-Ppi si lega all'H+-ATPasi trattata con tripsina. Il legame dell'attivatore avviene perciò ad un sito diverso da quello delle 14-3-3 e a monte del sito di taglio della tripsina
A novel interaction partner for the C-terminus of Arabidopsis thaliana plasma membrane H+-ATPase (AHA1 isoform): site and mechanism of action on H+-ATPase activity differ from those of 14-3-3 proteins
No full textUsing the two-hybrid technique we identi®ed a novel protein whose N-terminal 88 amino acids (aa)
interact with the C-terminal regulatory domain of the plasma membrane (PM) H+-ATPase from
Arabidopsis thaliana (aa 847±949 of isoform AHA1). The corresponding gene has been named Ppi1 for
Proton pump interactor 1. The encoded protein is 612 aa long and rich in charged and polar residues,
except for the extreme C-terminus, where it presents a hydrophobic stretch of 24 aa. Several genes in
the A. thaliana genome and many ESTs from different plant species share signi®cant similarity (50±70%
at the aa level over stretches of 200±600 aa) to Ppi1. The PPI1 N-terminus, expressed in bacteria as a
fusion protein with either GST or a His-tag, binds the PM H+-ATPase in overlay experiments. The same
fusion proteins and the entire coding region fused to GST stimulate H+-ATPase activity. The effect of the
His-tagged peptide is synergistic with that of fusicoccin (FC) and of tryptic removal of a C-terminal
10 kDa fragment. The His-tagged peptide binds also the trypsinised H+-ATPase. Altogether these results
indicate that PPI1 N-terminus is able to modulate the PM H+-ATPase activity by binding to a site
different from the 14-3-3 binding site and is located upstream of the trypsin cleavage site
Tyrosine phosphorylation inhibits the interaction of 14-3-3 proteins with the plant plasma membrane H+-ATPase
No full textInteraction of 14-3-3 proteins with their targets depends not only on the phosphorylation status of the target but also on that of 14-3-3 (Fu et al., 2000). In this work we demonstrated that the maize 14-3-3 isoform GF14-6 is a substrate of the tyrosine kinase insulin growth factor receptor 1. By means of site-directed mutants of GF14-6, we identified Tyr-137 as the specific tyrosine residue phosphorylated by the insulin growth factor receptor 1. Phosphorylation of GF14-6 on Tyr-137 lowered its affinity for a peptide mimicking the 14-3-3 binding site of the plant plasma membrane H+-ATPase. Moreover, phosphorylation in planta of 14-3-3 tyrosine residues, resulting from incubation with the tyrosine phosphatase inhibitor, phenylarsine oxide, decreased their association to the H+-ATPase
A phosphopeptide corresponding to the cytosolic stretch connecting transmembrane segments 8 and 9 of the plasma membrane H+-ATPase binds 14-3-3 proteins and inhibits fusicoccin induced activation of the H+-ATPase
No full text
Risk factors for complications and mortality of percutaneous endoscopic gastrostomy: A multicenter, retrospective study
No full textC-reactive protein; Gastroscopy; Mortality; Percutaneous endoscopic gastrostomy; Serum albumi
Otava eli suomalaisia huvituksia. 1. osa
No full textCarl Axel Gottlund (1796-1875) oli tutkija, lehtimies ja kirjailija, suomalaisuuden edistäjä. Hänen merkittävimpiä saavutuksiaan olivat Otawan julkaiseminen sekä tutkimukset Ruotsin ja Norjan nk. metsäsuomalaisista. Otawa oli Gottlundin itsensä kustantama ja lähes kokonaan kirjoittamakin ensimmäinen suomenkielinen kirjallis-taiteellinen albumi. Gottlund halusi näin osoittaa, että suomen kieltä voitiin käyttää erilaisten asioiden ilmaisemiseen kuten muitakin sivistyskieliä. Kirjakielenään Gottlund käytti savon murteen mukaelmaa.
Otawa sisältää tutkielmia Suomen historiasta, kieli- ja musiikkitieteellisiä artikkeleita, näytteitä kansanrunoudesta, Gottlundin omia runoja sekä runojen käännöksiä Sapfosta Bellmaniin. Otawan kuvittivat Magnus ja Wilhelm von Wright sekä Robert Ekman. Kustannuksia alentaakseen Gottlund maalasi itse albuminsa kivipiirrokset värillisiksi. Osa III julkaistiin vasta Gottlundin kuoleman jälkeen. Teoksen täydellisinä säilyneet kappaleet ovat erittäin harvinaisia
Otava eli suomalaisia huvituksia. 2. osa
No full textCarl Axel Gottlund (1796-1875) oli tutkija, lehtimies ja kirjailija, suomalaisuuden edistäjä. Hänen merkittävimpiä saavutuksiaan olivat Otawan julkaiseminen sekä tutkimukset Ruotsin ja Norjan nk. metsäsuomalaisista. Otawa oli Gottlundin itsensä kustantama ja lähes kokonaan kirjoittamakin ensimmäinen suomenkielinen kirjallis-taiteellinen albumi. Gottlund halusi näin osoittaa, että suomen kieltä voitiin käyttää erilaisten asioiden ilmaisemiseen kuten muitakin sivistyskieliä. Kirjakielenään Gottlund käytti savon murteen mukaelmaa.
Otawa sisältää tutkielmia Suomen historiasta, kieli- ja musiikkitieteellisiä artikkeleita, näytteitä kansanrunoudesta, Gottlundin omia runoja sekä runojen käännöksiä Sapfosta Bellmaniin. Otawan kuvittivat Magnus ja Wilhelm von Wright sekä Robert Ekman. Kustannuksia alentaakseen Gottlund maalasi itse albuminsa kivipiirrokset värillisiksi. Osa III julkaistiin vasta Gottlundin kuoleman jälkeen. Teoksen täydellisinä säilyneet kappaleet ovat erittäin harvinaisia
Characterization of the interaction between the plasma membrane H+-ATPase of Arabidopsis thaliana and a novel interactor (PPI1)
No full textProton pump interactor, isoform 1 (PPI1) is a novel interactor of the C-terminus of Arabidopsis thaliana plasma membrane H+-ATPase (EC 3.6.3.6) (Morandini P, Valera M, Albumi C, Bonza MC, Giacometti S, Ravera G, Murgia I, Soave C & De Michelis MI (2002) Plant J 31, 487-497). We produced two fusion proteins consisting of, respectively, the first 88 amino acids or the entire protein deleted of the last 24 hydrophobic amino acids, and we show that the latter protein has a threefold higher affinity for the H +-ATPase. PPI1-induced stimulation of H+-ATPase activity dramatically decreased with the increase of pH above pH 6.8, but became largely pH-independent when the enzyme C-terminus was displaced by fusicoccin-induced binding of 14-3-3 proteins. The latter treatment did not affect PPI1 affinity for the H+-ATPase. These results indicate that PPI1 can bind the H+-ATPase independently of the C-terminus conformation, but is not able to suppress the C-terminus auto-inhibitory action
