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001-es BibID:BIBFORM066467
Első szerző:Boratkó Anita (biokémikus, molekuláris biológus)
Cím:PKC mediated phosphorylation of TIMAP regulates PP1c activity and endothelial barrier function / Anita Boratkó, Csilla Csortos
Dátum:2017
ISSN:0167-4889
Megjegyzések:TGF-β inhibited membrane-associated protein (TIMAP) is greatly expressed in endothelial cell lines and serves as a protein phosphatase 1 (PP1) regulatory subunit. Phosphorylation state of TIMAP, through affecting PP1 activity, has a remarkable effect on endothelial barrier function. Here we present evidence for a previously unidentified PKC phosphorylation site in TIMAP. Protein-protein interaction was detected in pulmonary endothelial cells between endogenous TIMAP and activated PKCα. PKCα phosphorylated the full length recombinant TIMAP in in vitro kinase assay and Ser331 of TIMAP was shown to be phosphorylated by PKC. Phosphorylation of TIMAP upon PKC activation in endothelial cells results in enrichment of TIMAP in the membrane, but no such change can be observed in PKC depleted cells. However, the previously identified PKA/GSK-3β induced enrichment of TIMAP at the plasma membrane was not affected in the absence of PKC. Interaction between TIMAP and the TIMAP-PP1 substrate phospho-ERM was described earlier, but now we show that binding of PKC phosphorylated TIMAP to ERM is severely reduced. This suggests an inhibitory effect of phospho-Ser331 on TIMAP-PP1 activity toward phospho-ERM. Accordingly, phospho-ERM level in the membrane fraction of the phospho-mimic S331D TIMAP mutant transfected cells was increased, but the S331A mutant overexpressing endothelial cells had a lower phospho-ERM level. Consistent with the phospho-ERM level, electric resistance measurements showed that the S331A mutation of TIMAP resulted in faster recovery from the PMA treatment. Taken together, phosphorylation of TIMAP on Ser331 by PKC represents a new mechanism of endothelial barrier regulation, through the inhibition of phospho-ERM dephosphorylation.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochimica et Biophysica Acta (BBA). Molecular Cell Research. - 1864 : 2 (2017), p. 431-439. -
További szerzők:Csortos Csilla (1956-) (biokémikus)
Pályázati támogatás:PD116262(AB)
OTKA
Internet cím:DOI
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001-es BibID:BIBFORM047051
035-os BibID:PMID:2157500
Első szerző:Csortos Csilla (biokémikus)
Cím:Phosphorylase phosphatase activities of rat liver in streptozotocin-diabetes / Csilla Csortos, Ilona Farkas, Lloyd Sparks, Tamás Bányász, Tibor Kovács, Pál Gergely
Dátum:1990
ISSN:0167-4889
Megjegyzések:Protein phosphatase-1 and 2A, accounting for all the hepatic activity regulating phosphorylase, were assayed in streptozotocin-induced (8 weeks) diabetic Wistar rats. Cytosolic protein phosphatase-1 and 2A were distinguished by chromatography on heparin-Sepharose and by inhibition with inhibitor-2. Approx. 25-35% increases in type-1 phosphorylase phosphatase activity measured in cytosols were registered in diabetic rats when compared with control and 24 h fasting animals. The enrichment of protein phosphatase-1 in the cytosol of streptozotocin-treated rat livers could not be attributed to the reduced glycogen content with the onset of diabetes, since this elevated level of type-1 phosphatase was not observed in fasting rats with low glycogen content. The translocation of type-1 phosphatase from the particulate fraction into the cytosol was also recorded in trypsin-treated samples of diabetic rat livers. The apparent molecular weight of type-1 phosphatase in the cytosol of control and fasted rats was 160,000 as judged by gel filtration. The type-1 phosphatase activity that was released from the particulate fraction by streptozotocin-induced diabetes identified a further enzyme species (Mr 110,000) in the cytosol. Our data imply that the higher levels of cytosolic protein phosphatase-1 in diabetic rat liver could be a consequence of the dissociation of the catalytic subunit of protein phosphatase-1 and the glycogen-binding subunit in rat livers.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Protein phosphatase
Hepatic metabolism
Diabetes
Fasting
Streptozotocin
Rat liver
Megjelenés:Biochimica et Biophysica Acta (BBA). Molecular Cell Research. - 1052 : 1 (1990), p. 235-241. -
További szerzők:Farkas Ilona (1953-) (biokémikus) Sparks, Lloyd Bányász Tamás (1960-) (élettanász) Kovács Tibor (1929-1994) (élettanász) Gergely Pál (1947-) (biokémikus)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
DOI
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