A novel 14-kilodalton protein interacts with the mitogen-activated protein kinase scaffold mp1 on a late endosomal/lysosomal compartment |
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Authors: | Wunderlich W Fialka I Teis D Alpi A Pfeifer A Parton R G Lottspeich F Huber L A |
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Institution: | Research Institute of Molecular Pathology, A-1030 Vienna, Austria. |
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Abstract: | We have identified a novel, highly conserved protein of 14 kD copurifying with late endosomes/lysosomes on density gradients. The protein, now termed p14, is peripherally associated with the cytoplasmic face of late endosomes/lysosomes in a variety of different cell types.In a two-hybrid screen with p14 as a bait, we identified the mitogen-activated protein kinase (MAPK) scaffolding protein MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK) partner 1 (MP1) as an interacting protein. We confirmed the specificity of this interaction in vitro by glutathione S-transferase pull-down assays and by coimmunoprecipitation, cosedimentation on glycerol gradients, and colocalization. Moreover, expression of a plasma membrane-targeted p14 causes mislocalization of coexpressed MP1. In addition, we could reconstitute protein complexes containing the p14-MP1 complex associated with ERK and MEK in vitro.The interaction between p14 and MP1 suggests a MAPK scaffolding activity localized to the cytoplasmic surface of late endosomes/lysosomes, thereby combining catalytic scaffolding and subcellular compartmentalization as means to modulate MAPK signaling within a cell. |
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Keywords: | signal transduction scaffold MEK ERK subcellular localization endocytosis |
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