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001-es BibID:BIBFORM028726
Első szerző:Kiss Enikő
Cím:Integrin-linked kinase phosphorylates the myosin phosphatase target subunit at the inhibitory site in platelet cytoskeleton / Enikő Kiss, Andrea Murányi, Csilla Csortos, Pál Gergely, Masaaki Ito, David J. Hartshorne, Ferenc Erdődi
Dátum:2002
ISSN:0264-6021
Megjegyzések:The myosin phosphatase (MP) composed of the catalytic subunit of type 1 protein phosphatase and myosin phosphatase target subunit isoform 1 (MYPT1) was identified as the major serine/threonine phosphatase component in the platelet-cytoskeleton fraction. MYPT1 was phosphorylated by cytoskeletal kinase(s), but the identity of the kinase(s) and the effect of phosphorylation were not established. Incubation of platelet-cytoskeletal fraction with MgATP or MgATP[S] (magnesium adenosine 5'-[gamma-thio]triphosphate) caused a decrease in the 20 kDa light-chain of smooth-muscle myosin (MLC20) phosphatase and phosphorylase phosphatase activities. MYPT1 contains a phosphorylation site, Thr-695, involved in the inhibition of MP in a RhoA/Rho kinase-dependent manner. The cytoskeletal kinase(s) phosphorylated Thr-695 of glutathione S-transferase (GST)-MYPT1, as determined with an antibody specific for phosphorylated Thr-695. The level of Rho kinase was low in the cytoskeletal fraction and was detected primarily in the membrane and cytosolic fractions. The phosphorylation of Thr-695 by the cytoskeletal kinase(s) was not affected by Rho kinase inhibitor, Y-27632, suggesting that kinase(s) other than Rho kinase were involved. In-gel kinase assay identified a kinase at 54-59 kDa that phosphorylated the C-terminal fragment of MYPT1 (GST-MYPT1(667-1004)). Western blots detected both zipper-interacting protein kinase (ZIPK) and integrin-linked kinase (ILK) at 54-59 kDa in the cytoskeleton and membrane fractions. Cytoskeletal ZIPK and ILK were separated and partially purified by chromatography on SP-Sepharose and on MonoQ. ZIPK preferentially phosphorylated MLC20 and had low activity on MYPT1. ILK phosphorylated both MLC20 and MYPT1 and phosphorylation of MYPT1 occured on Thr-695. The above results raise the potential for regulation of MP activity in platelet cytoskeleton by ILK and suggest an alternative to the Rho-linked pathway.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Biochemical Journal. - 365 : 1 (2002), p. 79-87. -
További szerzők:Murányi Andrea (1966-) (biokémikus) Ito, Masaaki Hartshorne, David J. Erdődi Ferenc (1953-) (biokémikus) Csortos Csilla (1956-) (biokémikus) Gergely Pál (1947-) (biokémikus)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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2.

001-es BibID:BIBFORM028868
Első szerző:Murányi Andrea (biokémikus)
Cím:Identification and localization of myosin phosphatase in human platelets / Andrea Murányi, Ferenc Erdődi, Masaaki Ito, Pál Gergely, David J. Hartshorne
Dátum:1998
ISSN:0264-6021
Megjegyzések:Type 1 (PP1) and type 2A (PP2A) phosphatase activity was measured in three subcellular fractions of human platelets. About 80% of the activity was in the high-speed supernatant. Western blots showed that the catalytic subunit of PP1 (PP1c), including alpha- and delta-isoforms, was present in each fraction, but the level of the catalytic subunit of PP2A was very low in the low-speed pellet (cytoskeletal fraction). Various antibodies detected a subunit similar to the 130 kDa subunit (M130) of myosin phosphatase (MP) of smooth muscle in the low- and the high-speed pellets of human platelets. PP1c and associated proteins were isolated by microcystin-Sepharose. Many proteins were separated from each fraction, including myosin, actin and PP1c. M130 was separated only from the low-speed and the high-speed pellets. Kinase activities were detected in the unbound fractions, and fractions from the low- and high-speed pellets phosphorylated M130 and myosin respectively. Treatment of platelets with calyculin A increased the phosphorylation level of many proteins, including myosin heavy- and light-chains, and caused association of cytoskeletal proteins with the low-speed pellet. No marked change in the distribution of PP1c and M130 was detected. These results suggest that the MP in human platelets is composed of PP1c plus a subunit similar to M130 of the smooth muscle phosphatase.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:The Biochemical Journal. - 330 : 1 (1998), p. 225-231. -
További szerzők:Ito, Masaaki Hartshorne, David J. Erdődi Ferenc (1953-) (biokémikus) Gergely Pál (1947-) (biokémikus)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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3.

001-es BibID:BIBFORM028725
Első szerző:Murányi Andrea (biokémikus)
Cím:Phosphorylation of the myosin phosphatase target subunit by integrin-linked kinase / Andrea Murányi, Justin A. MacDonald, Jing Ti Deng, David P. Wilson, Timothy A. J. Haystead, Michael P. Walsh, Ferenc Erdődi, Enikő Kiss, Yue Wu, David J. Hartshorne
Dátum:2002
ISSN:0264-6021
Megjegyzések:A mechanism proposed for regulation of myosin phosphatase (MP) activity is phosphorylation of the myosin phosphatase target subunit (MYPT1). Integrin-linked kinase (ILK) is associated with the contractile machinery and can phosphorylate myosin at the myosin light-chain kinase sites. The possibility that ILK may also phosphorylate and regulate MP was investigated. ILK was associated with the MP holoenzyme, shown by Western blots and in-gel kinase assays. MYPT1 was phosphorylated by ILK and phosphorylation sites in the N- and C-terminal fragments of MYPT1 were detected. From sequence analyses, three sites were identified: a primary site at Thr(709), and two other sites at Thr(695) and Thr(495). One of the sites for cAMP-dependent protein kinase (PKA) was Ser(694). Assays with the catalytic subunit of type 1 phosphatase indicated that only the C-terminal fragment of MYPT1 phosphorylated by zipper-interacting protein kinase, and ILK inhibited activity. The phosphorylated N-terminal fragment activated phosphatase activity and phosphorylation by PKA was without effect. Using full-length MYPT1 constructs phosphorylated by various kinases it was shown that Rho kinase gave marked inhibition; ILK produced an intermediate level of inhibition, which was considerably reduced for the Thr(695)-->Ala mutant; and PKA had no effect. In summary, phosphorylation of the various sites indicated that Thr(695) was the major inhibitory site, Thr(709) had only a slight inhibitory effect and Ser(694) had no effect. The findings that ILK phosphorylated both MYPT1 and myosin and the association of ILK with MP suggest that ILK may influence cytoskeletal structure or function.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Biochemical Journal. - 366 (2002), p. 211-216. -
További szerzők:MacDonald, Justin A. Deng, Jing Ti Wilson, David P. Haystead, Timothy A. J. Walsh, Michael P. Kiss Enikő Wu, Yue Hartshorne, David J. Erdődi Ferenc (1953-) (biokémikus)
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