A type 2A protein phosphatase dephosphorylates the elongation factor 2 and is stimulated by the phorbol ester TPA in mouse epidermis in vivo
- 6 November 1989
- journal article
- Published by Wiley in FEBS Letters
- Vol. 257 (2) , 357-360
- https://doi.org/10.1016/0014-5793(89)81571-6
Abstract
Mouse epidermal cytosol contains a protein phosphatase with M r, 38000, which dephosphorylates the elongation factor 2 (EF-2) of protein biosynthesis and is stimulated after topical application of TPA to mouse skin [(1988) Biochem. Biophys. Res. Commun. 153, 1129-1135], Dephosphorylation of EF-2 by this phosphatase is inhibited by okadaic acid at concentrations as low as 10−8 M, but not by heparin up to concentrations of 600 . The catalytic subunit of protein phosphatase 2A (PP2Ac) with EF-2 as a substrate exhibits the same sensitivity towards okadaic acid and insensitivity towards heparin as the EF-2 phosphatase of epidermal cytosol. The catalytic subunit of protein phosphatase 1 (PP1c) is strongly suppressed by heparin and less sensitive towards okadaic acid than PP2Ac. PP2Ac is around 50 times more efficient in dephosphorylating EF-2 than PP1c. These data indicate that the TPA-stimulated EF-2 phosphatase in epidermal cytosol is a type 2A protein phosphatase.
Keywords
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