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A novel 14-kilodalton protein interacts with the mitogen-activated protein kinase scaffold mp1 on a late

W Wunderlich1, I Fialka, D Teis

  • 1Research Institute of Molecular Pathology, A-1030 Vienna, Austria.

The Journal of Cell Biology
|March 27, 2001
PubMed

Insights

Researchers discovered p14, a protein on late endosomes/lysosomes, interacting with MP1. This suggests a new way the mitogen-activated protein kinase (MAPK) pathway is controlled by organizing scaffolding proteins within specific cell compartments.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Signal Transduction

Background:

  • Late endosomes/lysosomes are crucial cellular organelles involved in degradation and sorting.
  • Mitogen-activated protein kinase (MAPK) pathways regulate diverse cellular processes.
  • Scaffolding proteins are essential for organizing signaling pathways.

Purpose of the Study:

  • To identify novel proteins associated with late endosomes/lysosomes.
  • To investigate the interaction between p14 and MAPK pathway components.
  • To elucidate the role of p14 in MAPK signaling localization.

Main Methods:

  • Density gradient centrifugation to isolate late endosomes/lysosomes.
  • Yeast two-hybrid screening to identify interacting proteins.
  • In vitro biochemical assays (GST pull-down, coimmunoprecipitation, glycerol gradient cosedimentation) to confirm interactions.
  • Colocalization studies and expression of targeted proteins to assess functional consequences.

Main Results:

  • A novel 14 kDa protein, p14, was identified associated with late endosomes/lysosomes.
  • p14 was found to interact with MAPK/ERK kinase (MEK) partner 1 (MP1), a MAPK scaffolding protein.
  • The p14-MP1 complex was reconstituted with ERK and MEK in vitro, and p14 expression affected MP1 localization.
  • The p14-MP1 interaction localizes MAPK scaffolding to the cytoplasmic face of late endosomes/lysosomes.

Conclusions:

  • p14 is a novel component of the late endosome/lysosome machinery.
  • The interaction of p14 with MP1 establishes a MAPK scaffolding function on late endosomes/lysosomes.
  • This compartmentalization of MAPK signaling provides a mechanism for precise regulation of cellular responses.

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