Regulation of MPF activity in vitro

Cell. 1988 Apr 22;53(2):185-95. doi: 10.1016/0092-8674(88)90380-7.


We have developed a soluble, cell-free system from premeiotic Xenopus oocytes that executes the post-translational activation of a precursor form of maturation promoting factor (MPF). We have distinguished at least two components of this ATP-dependent reaction: pre-MPF, a precursor to MPF that activates independently of added MPF and whose apparent molecular weight changes from 400 kd to 260 kd upon activation; and INH, an inhibitor of pre-MPF activation that confers MPF dependence on the reaction. We present evidence suggesting that INH is a phosphatase and that the activation of pre-MPF occurs via phosphorylation. INH activity itself seems to be regulated by another phosphatase, protein phosphatase-1. We have directly examined the pattern of protein phosphorylation during the activation reaction and have found 92 and 140 kd proteins whose phosphorylation increases when MPF activity appears. This system makes possible a direct examination of the regulation of MPF activity during the cell cycle.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Cycle
  • Female
  • Growth Substances / genetics*
  • Growth Substances / isolation & purification
  • Homeostasis
  • Maturation-Promoting Factor
  • Molecular Weight
  • Oocytes / cytology
  • Oocytes / metabolism*
  • Phosphates
  • Phosphoprotein Phosphatases / metabolism
  • Phosphorylation
  • Protein Phosphatase 1
  • Protein Processing, Post-Translational*
  • Xenopus laevis


  • Growth Substances
  • Phosphates
  • Maturation-Promoting Factor
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 1