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Updated: Aug 14, 2026

Radiolabeling and Quantification of Cellular Levels of Phosphoinositides by High Performance Liquid Chromatography-coupled Flow Scintillation
10:52

Radiolabeling and Quantification of Cellular Levels of Phosphoinositides by High Performance Liquid Chromatography-coupled Flow Scintillation

Published on: January 6, 2016

Phosphatidylinositol 3-kinase regulation of fluid phase endocytosis

M J Clague1, C Thorpe, A T Jones

  • 1Physiological Laboratory, University of Liverpool, UK.

FEBS Letters
|July 3, 1995
PubMed

Insights

Wortmannin, a fungal metabolite, inhibits fluid phase endocytosis in baby hamster kidney cells by targeting phosphatidylinositol 3-kinase (PI3K). This suggests PI3K

Area of Science:

  • Cell Biology
  • Biochemistry

Background:

  • Endocytosis is a fundamental cellular process for internalizing molecules and regulating cell surface receptors.
  • Phosphatidylinositol 3-kinase (PI3K) is a key enzyme involved in various cellular signaling pathways, including those related to cell growth and survival.
  • Wortmannin is a known inhibitor of PI3K, widely used to study its cellular functions.

Purpose of the Study:

  • To investigate the role of wortmannin and its target, PI3K, in the process of endocytosis.
  • To elucidate the effects of PI3K inhibition on the kinetics and efficiency of fluid phase endocytosis.

Main Methods:

  • Utilizing baby hamster kidney (BHK) cells for cellular experiments.
  • Employing horse radish peroxidase (HRP) as a fluid phase marker to quantify endocytosis.
  • Treating cells with varying concentrations of wortmannin to determine the IC50 value.
  • Analyzing the kinetics of HRP uptake and endosome volume.

Main Results:

  • Wortmannin significantly inhibits fluid phase endocytosis with an IC50 of approximately 5 nM.
  • Inhibition of endocytosis correlates with a >50% decrease in the initial rate of marker internalization.
  • Treatment leads to a reduced early endosome volume and enhanced marker recycling.

Conclusions:

  • The data strongly suggest that PI3K plays a critical role in regulating endocytosis.
  • Receptor activation, through its interaction with PI3K, may be coupled to receptor internalization and downregulation via PI3K-mediated endocytosis.

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