Polyamine stimulation of protein phosphatase-2A from rat liver using a non-protein phosphoester substrate.

Journal Article (Journal Article)

The polyamines, spermine and spermidine, activate a high molecular weight form of phosphorylase a phosphatase isolated from rat liver. This broad specificity protein phosphatase (type 2A) was partially purified, using both protein and non-protein phosphoester substrates. Spermine and spermidine activated isolated protein phosphatase-2A1 (apparent Mr 210,000) approximately 2-fold, when p-nitrophenyl phosphate (PNPP) was used as substrate. Freeze-thawing, which activated the phosphatase activity against a variety of phosphoprotein substrates, also increased the extent of stimulation of PNPP phosphatase activity by spermine (8 to 9-fold with Ka of 93 microM) and spermidine (6 to 7-fold with Ka 280 microM). Kinetic analysis indicated that the activation of phosphatase by polyamines was accomplished by an increase in Vmax of the enzyme, by a mechanism independent of that achieved by other cations. The data indicate that polyamines, at physiological concentrations, can activate a form of protein phosphatase widely distributed in mammalian tissues, and thereby influence cellular protein phosphorylation.

Full Text

Duke Authors

Cited Authors

  • Cornwell, T; Mehta, P; Shenolikar, S

Published Date

  • 1986

Published In

Volume / Issue

  • 11 / 5

Start / End Page

  • 373 - 382

PubMed ID

  • 3040820

International Standard Serial Number (ISSN)

  • 0746-3898


  • eng

Conference Location

  • United States