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001-es BibID:	BIBFORM027872
Első szerző:	Ayaydin, Ferhan
Cím:	Inhibition of serine/threonine-specific protein phosphatases causes premature activation of cdc2MsF kinase at G2/M transition and early mitotic microtubule organisation in alfalfa / Ferhan Ayaydin, Emese Vissi, Tamás Mészáros, Pál Miskolczi, Izabella Kovács, Attila Fehér, Viktor Dombrádi, Ferenc Erdődi, Pál Gergely, Dénes Dudits
Dátum:	2000
Megjegyzések:	Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34cdc2/CDC28-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 microM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 microM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 microM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban serine/threonine phosphatases chromosome condensation preprophase band Cdc2-related kinase endothall Medicago sativa L egyetemen (Magyarországon) készült közlemény
Megjelenés:	The Plant Journal. - 23 : 1 (2000), p. 85-96. -
További szerzők:	Mészáros Tamás (Szeged) Miskolczi Pál (Szeged) Kovács Izabella (Szeged) Fehér Attila (Szeged) Dudits Dénes Vissi Emese (1968-) (biokémikus, biológus) Dombrádi Viktor (1953-) (biokémikus) Erdődi Ferenc (1953-) (biokémikus) Gergely Pál (1947-) (biokémikus)
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001-es BibID:	BIBFORM027871
Első szerző:	Csordás Tóth Éva
Cím:	Protein phosphatase 2A holoenzyme and its subunits from Medicago sativa / Éva Csordás Tóth, Emese Vissi, Izabella Kovács, Attila Szőke, Joaquín Ariño, Pál Gergely, Dénes Dudits, Viktor Dombrádi
Dátum:	2000
ISSN:	0167-4412
Megjegyzések:	We detected an about 200 kDa holoenzyme of protein phosphatase 2A (PP2A) in the crude extract of Medicago sativa microcallus cells by gel permeation chromatography. By polymerase chain reaction (PCR) we isolated two M. sativa cDNA fragments corresponding to the catalytic (C) subunit, and one each coding for the A and the B regulatory subunits of PP2A. The C subunit sequences were different from that published previously, indicating the existence of at least three different isoforms in M. sativa. Using the PCR fragments as probes, we obtained two distinct full-length clones for both the A and B subunits from an alfalfa cDNA library. Our results demonstrate that the components of the PP2A holoenzyme, namely the catalytic and regulatory subunits, are present in alfalfa in several isoforms and that their sequences are highly similar to their plant, yeast and animal counterparts. The distinct regulatory subunit genes are constitutively expressed during the cell cycle. Interestingly, two A-B subunit pairs had parallel mRNA steady-state levels in different plant tissues suggesting that not all of the possible isoform combinations are present in all tissues. The expression of the MsPP2A Bbeta subunit form was induced by abscisic acid indicating a specific function for this protein in the stress response.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban cDNA cloning quaternary structure Ser/Thr protein phosphatase stress response tissue-specific expression
Megjelenés:	Plant Molecular Biology. - 43 : 4 (2000), p. 527-536. -
További szerzők:	Kovács Izabella (Szeged) Szőke Attila Ariño, Joaquín Dudits Dénes Vissi Emese (1968-) (biokémikus, biológus) Gergely Pál (1947-) (biokémikus) Dombrádi Viktor (1953-) (biokémikus)
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001-es BibID:	BIBFORM027917
Első szerző:	Vissi Emese (biokémikus, biológus)
Cím:	Protein phosphatase 1 catalytic subunit isoforms from alfalfa : biochemical characterization and cDNA cloning / Emese Vissi, Éva Csordás Tóth, Izabella Kovács, Zoltán Magyar, Gábor V. Horváth, Péter Bagossi, Pál Gergely, Dénes Dudits, Viktor Dombrádi
Dátum:	1998
Megjegyzések:	The catalytic subunit of protein phosphatase 1 (PP1c) was purified from an alfalfa (Medicago sativa) microcallus cell culture. The preparation was inhibited by rabbit muscle inhibitor-2 and okadaic acid and had a molecular mass of 35 kDa. Five distinct cDNAs termed MsPP1alpha, -beta, -gamma, -delta, and -epsilon were cloned from a M. sativa somatic embryo library. MsPP1alpha was identical to a cDNA reported earlier [A. Páy, M. Pirck, L. Bögre, H. Hirt, and E. Heberle-Bors Mol. Gen. Genet. 244, 176-182, 1994], while the others represented novel isoforms encoded by separate genes. The predicted amino acid sequences of MsPP1alpha, -beta, -gamma, -delta, and -epsilon were highly similar to each other and to other known PP1c sequences. The GST-MsPP1ss fusion protein expressed in Escherichia coli was catalytically active and was inhibited by inhibitor-2 and okadaic acid. Affinity-purified polyclonal MsPP1antipeptide antibody detected a protein of 36 kDa in crude cell extracts. These results proved that the cDNA clone encoded an active PP1c which was very similar to the purified enzyme. The mRNA and protein concentrations of PP1c as well as the specific activity of protein phosphatase 1 did not change during the cell cycle in a synchronized alfalfa cell culture. On the other hand, the isoforms exhibited different steady-state mRNA levels in different plant organs suggesting tissue-specific functions.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban protein phosphatase1 Medicago sativa protein purification cDNA sequencing cell cycle gene expression egyetemen (Magyarországon) készült közlemény
Megjelenés:	Archives of Biochemistry and Biophysics. - 360 : 2 (1998), p. 206-214. -
További szerzők:	Csordás Tóth Éva Kovács Izabella (Szeged) Magyar Zoltán Horváth Gábor V. Bagossi Péter (1966-2011) (biokémikus, vegyész) Dudits Dénes Gergely Pál (1947-) (biokémikus) Dombrádi Viktor (1953-) (biokémikus)
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