Identification and localization of myosin phosphatase in human platelets

Andrea Murányi, F. Erdődi, Masaaki Ito, P. Gergely, David J. Hartshorne

Research output: Contribution to journalArticle

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Abstract

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 α- and δ-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.

Original languageEnglish
Pages (from-to)225-231
Number of pages7
JournalBiochemical Journal
Volume330
Issue number1
Publication statusPublished - Feb 15 1998

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Myosin-Light-Chain Phosphatase
Platelets
Blood Platelets
Myosins
Phosphoric Monoester Hydrolases
Smooth Muscle
Catalytic Domain
Myosin Light Chains
Proteins
Cytoskeletal Proteins
Subcellular Fractions
Myosin Heavy Chains
Sepharose
Muscle
Actins
Protein Isoforms
Phosphotransferases
Western Blotting
Phosphorylation
Antibodies

ASJC Scopus subject areas

  • Biochemistry

Cite this

Identification and localization of myosin phosphatase in human platelets. / Murányi, Andrea; Erdődi, F.; Ito, Masaaki; Gergely, P.; Hartshorne, David J.

In: Biochemical Journal, Vol. 330, No. 1, 15.02.1998, p. 225-231.

Research output: Contribution to journalArticle

Murányi, A, Erdődi, F, Ito, M, Gergely, P & Hartshorne, DJ 1998, 'Identification and localization of myosin phosphatase in human platelets', Biochemical Journal, vol. 330, no. 1, pp. 225-231.
Murányi, Andrea ; Erdődi, F. ; Ito, Masaaki ; Gergely, P. ; Hartshorne, David J. / Identification and localization of myosin phosphatase in human platelets. In: Biochemical Journal. 1998 ; Vol. 330, No. 1. pp. 225-231.
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