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Updated: Aug 13, 2026

Examining BCL-2 Family Function with Large Unilamellar Vesicles
08:35

Examining BCL-2 Family Function with Large Unilamellar Vesicles

Published on: October 5, 2012

Pim kinases phosphorylate multiple sites on Bad and promote 14-3-3 binding and dissociation from Bcl-XL

Andrew Macdonald1, David G Campbell, Rachel Toth

  • 1MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK. a.macdonald@dundee.ac.uk

BMC Cell Biology
|January 13, 2006
PubMed
Abstract

Insights

Pim kinases phosphorylate the Bad protein at multiple sites, influencing its function and potentially inhibiting cell death. This research clarifies how Pim kinases interact with Bad, offering insights into cancer cell proliferation.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Cancer Research

Background:

  • Pim kinases (Pim-1, 2, 3) are calcium/calmodulin-dependent protein kinases implicated in cancer.
  • Overexpression of Pim-1 and Pim-2 is linked to lymphoma development in mice.
  • Elevated Pim expression is observed in various human cancers.

Purpose of the Study:

  • To investigate the phosphorylation activity of Pim kinases on the Bcl-2 family member Bad.
  • To identify specific phosphorylation sites on Bad by Pim kinases.
  • To elucidate the functional consequences of Pim-mediated Bad phosphorylation.

Main Methods:

  • In vitro kinase assays using purified Pim kinases and Bad protein.
  • Expression of Pim kinases and Bad in HEK-293 cells.
  • Site-directed mutagenesis of Bad phosphorylation residues.
  • Analysis of Bad protein interactions with 14-3-3 and Bcl-XL.

Main Results:

  • Pim kinases constitutively phosphorylate Bad at Ser112, Ser136, and Ser155.
  • Pim-2 primarily phosphorylates Ser112; Pim-1 phosphorylates Ser112, Ser136, and Ser155; Pim-3 shows broader specificity, including Ser170.
  • Phosphorylation of Ser136 is crucial for subsequent phosphorylation of Ser112 and Ser155.
  • Pim phosphorylation promotes Bad binding to 14-3-3 and inhibits its association with Bcl-XL.

Conclusions:

  • All three Pim kinases phosphorylate Bad, primarily at Ser112, and multiple other sites.
  • Pim-mediated phosphorylation of Bad inhibits its pro-apoptotic function.
  • These findings support the role of Pim kinases in promoting cell proliferation and survival.

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