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Glucose-induced regulation of protein import receptor Tom22 by cytosolic and mitochondria-bound kinases.

Authors
  • Gerbeth, Carolin
  • Schmidt, Oliver
  • Rao, Sanjana
  • Harbauer, Angelika B
  • Mikropoulou, Despina
  • Opalińska, Magdalena
  • Guiard, Bernard
  • Pfanner, Nikolaus
  • Meisinger, Chris
Type
Published Article
Journal
Cell Metabolism
Publisher
Elsevier
Publication Date
Oct 01, 2013
Volume
18
Issue
4
Pages
578–587
Identifiers
DOI: 10.1016/j.cmet.2013.09.006
PMID: 24093680
Source
Medline
License
Unknown

Abstract

Most mitochondrial proteins are imported by the translocase of the outer mitochondrial membrane (TOM). Tom22 functions as central receptor and transfers preproteins to the import pore. Casein kinase 2 (CK2) constitutively phosphorylates the cytosolic precursor of Tom22 at Ser44 and Ser46 and, thus, promotes its import. It is unknown whether Tom22 is regulated under different metabolic conditions. We report that CK1, which is involved in glucose-induced signal transduction, is bound to mitochondria. CK1 phosphorylates Tom22 at Thr57 and stimulates the assembly of Tom22 and Tom20. In contrast, protein kinase A (PKA), which is also activated by the addition of glucose, phosphorylates the precursor of Tom22 at Thr76 and impairs its import. Thus, PKA functions in an opposite manner to CK1 and CK2. Our results reveal that three kinases regulate the import and assembly of Tom22, demonstrating that the central receptor is a major target for the posttranslational regulation of mitochondrial protein import.

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